4" Apochromatic Hyper Shootout by Daniel Mounsey

https://www.cloudynights.com/topic/100005-4-apochromatic-hyper-shootout/page-11#entry2381946

INTRODUCTION:

This review is only for the cloudynights. I have decided that I have no intent to share it anywhere else as long as CN wants to keep it, and the review can stay in it's unedited form. Today we will compare 4” refractors on an unprecedented level. We will reveal which ones were good, which ones were great, and which ones were at the absolute pinnacle in a side by side, visual shootout. This was a monumental task and I’m glad it’s finally over because after finishing it, you guys are on your own. There may be a number of clerical errors here and there, so forgive me, I wrote this myself and it's a lot to write.

I wonna thank Farah Payan for her strong support. I could never have done this without her. I’d also like to thank a great observing buddy of mine, June Trajano, who’s always participated in these types of tests over the years and offers valuable input for me. June and I have been observing for quite a while and I’ve always respected his opinion and critical eyes. I’d also like to thank Ridwan Angkasa for spending so much time conducting tests. Ridwan has an amazing ambition with visual testing and I have a great deal of respect for him. I’d also like to offer a special thanks to all the guys who assisted with loaning their telescopes in order to make this review a reality.

NOTICE

The reason this review was so delayed is because I had second thoughts about posting it. I have to set an example because of what I represent with cloudynights and this industry and it's a huge responsibilty to take on because of who I am. It is extremely difficult to go in open forum and lay it all on the line as I've done here. It is not my intent to bash any company and I've tried to be as constructive, yet critical as possible. This must be clearly stated.

THE CONTENDERS FOR THIS PARTICULAR REVIEW

Some of these refractors were tested side by side, while others were tested during other periods. In some cases we had multiples of the same model. This would allow us an opportunity to see how consistent they were. I’ve tested various other 4” refractors on numerous occasions, but they were not picked as part of this comparison. Note that OTA stands for (optical tube assembly).

Antares 4” F-15 achromat
Orion 100ED
Takahashi FS102 (lost count)
Takahashi FC100 (lost count)
Takahashi TSA102 (four units)
Takahashi FSQ106 “Q” (two units)
Televue NP101 (two units)
Televue 101
Televue 102IS
TMB102
TMB115
Vixen 103ED
Vixen 100ED
William Optics FLT110/TEC optic
William Optics FLT110/TMB optic design (two units)
William Optics Megrez 110

Some observers asked to have the Stellarvue refractors as part of this comparison and I was offered to barrow a couple. This review could be given an update if I set the time aside to do so and people want it enough. If there is a telescope you do not see here that you were interested in, don't worry too much. Many of today's refractors are coming from the same plants over seas with different names stamped on them with a few cosmetic changes. This is why new brands are popping up all over the place. If you still have questions on a 4" refractor not tested here, then I'll try and offer some insight if possible.

COLOR CORRECTION AND CONTRAST HYPE

There are a good number of observers who appear to be under the impression that refractors, which exhibit some minor false color on stars, have less contrast than ones that doesn’t. I can assure you this is not always the case and in my opinion, it sends a red flag about the observer’s judgment and experience regarding the true quality of the telescope. There are various other factors, which could also potentially influence the contrast. One of the things I look at is the amount of spherical aberration the optic has or whether there are zones in the star test. There are give and takes to all the possibilities in fact there is no such thing as an optic that doesn’t have an aberration. Even eyepieces can introduce false color. How much of it we are willing to accept is probably what matters most, therefore I wouldn’t suggest you write a refractor off because someone tells you it exhibits a bit of false color.

I’ve seen a surprising amount of experienced observers do this without even qualifying the instrument in a number of other important ways to be sure about the true quality of the telescope. I will also tell you that there are even long achromats with wonderful contrast that very few have had the opportunity to look through. A decent refractor that is properly made has the potential to produce beautiful image quality on deep sky and planets whether it’s a doublet or triplet. I don’t want to give the impression that having excellent color correction is not an important factor but more so, to help prevent beginners and even some experienced observers from being so overly critical with it, that it clouds their overall judgement and it has easily proven to do so in many cases. If I had two refractors, which produced good images and one of them had less false color than the other, then of course, I’d pick the one that had less false color.

OH MY, THERE’S A SPECK OF DUST IN MY NEW OPTIC

The psychological effect of a few dust particles, which have absolutely no effect on optical quality are far less important than the possibility that the optic you already possess, may be that extra special scope out of the batch. In other words, you are blowing a perfectly good opportunity, which very few have, to discover that you may or may not already have an exceptionally great optic. In my opinion it’s a foolish mistake to send a new telescope back because of a few specs of dust without even testing it for something far more damaging called spherical aberration. Unfortunately though, there are some cases where the amount of dust is unacceptable as you are about to see.

JUDGING CONTRAST

I would describe contrast as a striking dissimilarity in pigmentation between features. Pretend we have two telescopes of equal aperture. Should we assume that because one telescope yields a darker background, that automatically means it has higher contrast? In my opinion no. Assuming both telescopes are of equal aperture, it’s quite possible that one instrument may not be transmitting as much light at the eyepiece for whatever the reason and you could mistakenly interpret that to mean it has higher contrast. A better way to test for contrast is to point both telescopes a star cluster for example and observe how the fainter stars appear in each instrument. If one telescope is revealing the faintest stars just as brightly as the other instrument and it still yields a darker background, then it’s probably safe to say it has higher contrast.

HOW DO YOU KNOW YOU HAVE A GREAT OPTIC?

The simple answer is that you don’t no matter what kind of glass it has. Even for opticians, it can be difficult to fully predict how well the glass will behave when exposed to various climates in the field when the telescope is under scrutiny. I’ve tested unacceptable refractors from all the best companies in the world that range from 80mm to 200mm. In some cases, very few of the same brand of refractor will perform exactly the same. I’m sure it’s similar to the way two of the same brand of guitars sound to a purist. They may sound very close, but very few will sound exactly the same.

THOMAS BACK’S STAR TESTING ESSAY

I personally prefer not to state how bright a star should be or what magnification you should use during the star test, there are too many variables involved here. With that said, you will have to feel out what works best in your particular case, but one of the best essays I’ve seen was written by Thomas Back of TMB Optical who sadly, is no longer with us. I strongly urge you to take the time to read this, and you will have a better understanding of what to expect out of your own refractor. Back also explains the importance of using color filters during the star test in certain refractors.

http://www.tmboptica...d.asp?cat_id=31

HOW I TEST OPTICS USING THE AIRY DISC

There are a number of things that should also be considered but in my opinion, this one plays a significant role on how I judge an optic and this is one of the things I examine. Just about any refractor can reveal an airy disc when the air stability is good, even if the optic has a number of optical aberrations, but there’s an exception. What you don’t want to see is that extraneous junk around the airy disc while the star is in focus regardless of whether it's a doublet, triplet or quadruplet. The same rules apply to all of them. This unfocused light will have a direct effect on how much sharpness and contrast a planet will appear to have at higher magnifications.

The airy disc is simply the concentrated light from a star, focused to a single point in the eyepiece. What you should see is the airy disc, along with a few faint and ill defined outer rings, which trickle in and out while being viewed through Earth’s atmosphere but this will also depend on the brightness of the star and the seeing conditions. This is the sign of an excellent optic in its purist visual state. Whenever I examine the quality of any refractor on a good night, this is one of the things I’m looking for when the star is in focus.

THE STAR TEST AND UNDER-CORRECTION

You'll notice that I focus on this quite a bit because it's common to see it. Under-correction occurs when light rays from the outer parameter of the optic converge inward faster or closer than light rays from the central area. The symptom is typically a fuzzier picture with a brighter central core and a less prominent outer ring while outside of focus. Over-correction is just the opposite.

One can tell if too much under-correction exists, even while focusing on a planet, it doesn’t even have to be a star! Two refractors may appear very close to the same under the seeing conditions most observers endure, but there are still going to be slight and possibly even severe differences in sharpness and contrast on the better nights of seeing which purists will appreciate at higher magnifications.

IS UNDER-CORRECTION COMMON

Yes. It’s very common for an optic to have some degree of under-correction, in fact a refractor simply by its nature will usually be in this state as it acclimates closer to the surrounding temperature and even then, it can exist, so don't panic every time you see this. The key is learning how much is acceptable. Some of the highest quality refractors in the world will show some degree of this while they acclimate.

A good 8” triplet can take as long as three, whopping hours before reaching its best spherical correction, depending on the temperature drop and the behavior of the glass. When a refractor reaches this state, that’s when it really begins to shine and the most subtle planetary features come alive! I’ve even seen the same instrument produce slightly different star tests on different nights because of the different climates the optics must endure. Even eyepieces can influence the star test, so I’d suggest you approach this with a very open mind and take your time. I personally prefer Naglers for star testing on axis.

Test your telescope over the course of several nights and examine how the optic behaves on average when the temperature and seeing conditions are still in question. It’s frustrating when impatient observers expect results right away. Bad seeing conditions can mimic aberrations or under-correction because as you rack the focus out, the rings are typically focused over turbulent air which can smear them. Jet streams and bad seeing can easily be verified by pointing the telescope at the Moon or planets. Rack the focus slightly outward and you will probably see a jet stream flowing across the field.

WHAT ABOUT OPTICAL CERTIFICATES

I remember a person who was adimant about getting an optical certificate with his refractor. I could tell he didn’t have much experience evaluating optics himself and any visual observer who knows this, soon finds out that a document doesn’t necessarily answer this question. Many observers seek answers in optical certificates in order to feel justified in paying the big bucks, or they just think it will determine whether they have a good optic or not. If that were the case, then there are some odd certificates floating around. In my opinion, this is something you should learn to do on your own. As for me, optical certificates serve little purpose. I can test the telescope myself over the course of a few nights, depending on the conditions and tell quite easily if it’s actually as good as the papers claim.

I’ve seen optics, which may seem impressive on a document go astigmatic in the winter seasons. On paper, everything looks nice but glass usually has a personality of its own when exposed to varying temperatures. What takes no prisoners is good seeing, steady temperatures, determination, guts, skill, patience and a keen eye because in reality, these are the things you'll need in order to see what a scope can really dish out. If you don’t think your eyes are keen enough, then I see little reason to be so obsessed with the issue. What you don’t see wonte hurt.

WHICH IS BETTER, DOUBLET OR TRIPLET

Any refractor that is properly made, has the potential to deliver fine images regardless of whether it’s a doublet, triplet or quadruplet design based on my personal experiences with all of them. I would not concern myself with the topic of extra glass but more so, the issue of the steep, curved shapes of the glass. By this I mean that having all these pieces of glass working in harmony with eachother to extreme tight tollorances as they do, is a monumental achievement when it's pulled off! Today’s coatings and figuring technology are absolutely amazing when you think about it.

My leaning towards longer doublets has more to do with their behavior under climate change and the forgiveness they have regarding collimation. Triplets are nearly impossible to realign, should the elements accidentally shift out of place even just a tiny bit. There is absolutely no room for error. Doublets are user friendly and adjustments between the elements themselves can even be made at home in some cases. Ridwan Angkasa actually does this.

WARM VS. COLD

This is one of the main issues I addressed some years back in a planetary eyepiece review because I noticed that it was constantly being overlooked by even some of the most experienced observers in the world and it was a topic that was not tapped into yet, or at least as far as I know. I also believe that the topic needs some scientific study but from a visual standpoint, I’ll express what takes place. There are some cases where either the glass or possibly the coatings will influence the images seen in a telescope or an eyepiece. I have come to find that most purists have a bias for cold images.

Warm is simply a term used to describe an optic that has a slight coffee tone or yellowness, while cold represents a bright, white or crystal clear image that is completely neautral. We can think of cold as favoring the blue while warm favors the yellow. For most deep sky targets, I prefer an optic that produces cold images, with the exception of viewing Jupiter in particular and sometimes Saturn but it also depends on the magnifications used, particularly with the rings.

If you take an 82 wratten light blue filter and view Jupiter, you’ll notice that Jupiter’s equatorials belts will become darker and therefore you may interpret that as having more contrast. But, there’s a negative trade off that must be considered. The trade off comes at the cost of losing some of the color fidelity the planet has to offer because Jupiter’s belts now take on a more monochrome appearance. This is one of the reasons why I actually don’t like images to be cold while viewing Jupiter. I still use Televue plossls as a planetary eyepiece for Jupiter because they are slightly warm. They are the only eyepieces in production that have a warmer tint to them while the Clave of Paris are the warmest I’ve ever seen. Telescopes behave in the same manner.

Some observers misunderstand how filters behave because they just expect them to make features pop into view. In order for a filter to work, the feature under scrutiny needs to be visible to some reasonable degree first before the filter can accentuate it. I personally can’t stand filters because most of them are so much darker than they need to be and many of them ghost too much, probably because they need good coatings. With filters being as dark as they are, they take away the natural color and beauty planets have to offer. There are some cases where highly experienced visual observers like Carlos Hernandez or Sol Robbins benefit from them and that makes perfect sense because they're more interested in documenting a specific feature and filters can sometimes help in this case.

I sometimes use a very special 48mm warming filter and a #82 light blue filter for planets made by B+W optics of Germany. They are the only brand of filters I use. Other than that, I don’t use color filters at all. I often use the warming filter on Jupiter and don't always have to be as concerned whether or not the eyepiece produces the warmth I want. Every observer is different, so it just depends on what you like.

CHECK YOUR DIAGONAL

Being involved sales, it doesn’t take long to notice what people are sold on. As soon as they hear the term 99% dialectric! they automatically assume it’s a great diagonal. This has become a big marketing strategy. Observers should be aware that many of these diagonals are mass produced over seas and just because it’s a dialectric diagonal doesn’t mean it has a smooth figure or that the application of the coatings is great either. This is often overlooked because people have become so obsessed with hearing the term “dialectric”! The precision or accuracy of the glass should not be ignored and the telescope is only as good as its weakest link. I'm not suggesting you become obsessed with this, I'm merely indicating you be aware of it. Not everyone can afford special diagonals.

The only diagonals we used for this particular comparison were two different Vernonscope diagonals and two Everbrite diagonals from Televue. My personal favorites are the Vernonscope models and the Baader Planetarium prism. This opinion is based on a number of very careful side by side comparisons that are not part of this review. No other diagonals were to be used in this comparison only because I wanted to keep everything as simple as possible. Sometimes we would even switch them around just to see if they introduced any positive or negative results. They were all very good.

EYEPIECES

Since I’ve been pretty impressed with the Pentax XW line and Nagler T6 series lately, I decided that they would be the only eyepieces used for this comparison and no others, mainly because of their short focal lengths and comfortable eye relief for these evaluations, particularly the XW’s. Focal lengths ranged anywhere from 3.5mm on up to 13mm. By the way, I highly recommend plossls or high quality orthos with good glass and optical coatings for planetary observations.

WHY I PREFER LIGHT POLLUTION

These tests all took place from a bright city. Observers often think that light pollution hinders planetary observations and it's probably the biggest myth of all time in astronomy. I actually prefer light pollution while viewing planets, it’s more soothing on the eyes and in some cases I’ll even leave an ambient light on as long as it’s not shining directly into the eyepiece. The reason I do this sometimes is to help prevent my eyes from becoming dark adapted. One of the worse things to have is a dark adapted eye while viewing planets. There are technical reasons for this. My perception of color and sharpness are usually improved this way and the best views of planets I’ve ever encountered were right at sundown, as soon as the planets first become visible and no stars are even visiable. This helps reduce light scatter, caused from overwhelming contrast and sharpens planetary edges. This fact has also been shared by many expert planetary
observers.

LETS GET DOWN TO BUSINESS

On the evening of February 24th 2007, June, Ridwan and myself set out on a quest to find some answers about today’s 4” apochromats. The tests would continue for the next year. This particular night would grant us seeing that was an 8.5 on a scale of 1-10 and it would be Ridwan’s first night under real steady skies. Although Ridwan was new to these comparisons, his eyes are alarmingly trained since he's a professional wedding photographer and teaches me more about colors then I'll ever understand. We had several apochromats from various companies.

ANTARES 4” F-15 ACHROMAT vs. ORION 100ED

We started our first comparison with the more affordable models here. The Antares achromat is a pretty scope to look at with its 1500mm focal length. I don’t know what it is with these two scopes, we just had so much fun with them. There’s a feeling of history I get when I look at the Antares 4” F-15, which is the intension Antares has. We first started out by giving all the scopes some ample time to settle down. We then paired the two scopes up side by side on an EM200 mount. We used an 11mm T6 and 7mm XW in the Antares to get 136x and 214x on Saturn while the 100ED had a 7mm XW and 5mm XW to give 143x and 200x. We would play with the magnifications and switch out eyepiece to clarify any issues like warmth or coldness in the image.

The first thing that surprised us all was how sharp the Orion ED100 was on Saturn. The Antares gproduced a more natural and beautiful warmth to the image, so we switched to the Pentax XW’s to see if the Nagler had any influence on this and it was definitely the optic of the telescope itself. The Orion 100ED continually pumped out a tighter and sharper image and this really surprised us all. If anything, I would have expected the Antares to at least equal or slightly surpass the 100ED in sharpness. We switched diagonals for clarification too. Even with the Orion 100ED at slightly higher magnifications, it was still about 7% or 10% sharper than the Antares in my apparent visual estimation and everyone agreed. Some observers say you can't see a 7% difference, oh well. June and I were both still impressed with the appearance of a more natural or colorful appearance in the Antares, but this was purely cosmetic and I actually prefer this effect more so on
Jupiter.

We also noticed that the background in the Antares was definitely darker than the 100ED, as if it had more contrast, but the moons around Saturn were not as obvious and we would soon find out it was not a gain in contrast, but more so, an actual loss of light from lack of better optical coatings in my opinion, at least on this particular unit. I believe that if the Antares had better optical coatings, it would have taken it up another notch in performance. I looked at the objective coatings and noticed they were very thin and it was easy to see my own reflections in them. A good amount of multi coatings makes it harder to see your own reflections. The moons around Saturn in the 100ED were more distinct while they appeared dim or in & out with the Antares. Over all, we agreed that the Orion 100ED was the winner here. Honestly, the Orion is fantastic for the money and an absolute bargain in my opinion. The color correction in both scopes were good, with
the Antares having a slight bit more of false color. This can sometimes fluctuate with the seeing but it was a steady night overall. June and I really loved the Antares and I'll bet that if we had another unit, it's quite possible that it could have done better. I would still highly recommend the Antares and would be happy to own one myself.

1st place Orion 100ED, 2nd place Antares 4" F-15

VIXEN 103ED vs. VIXEN 100ED

Vixen’s been around for a long time. I’ve always liked their older fluorite 102’s and even their 102 achromats back in the day. If you can find one, I highly recommend them. Those ones carried the Celestron name but were true Vixen’s underneath and observers should not under estimate them either. The Vixen 100ED doublet is basically the same scope as the Orion 100ED with different cosmetics but each one happened to perform very similar, which is quite an accomplishment if you ask me. The 103ED is another thing in itself. The 795mm F-7.7 103ED is Vixen’s flagship model at twice the price of the 100ED. When comparing the two scopes on Saturn, there were some interesting differences worth mentioning but we all still had some mixed thoughts here. We pushed the 103ED to 160x and the 100ED to 143x and 200x. We later found that the color correction was a bit better in the 103ED compared to the 1000mm F-10 100ED. The images were also noticeably brighter, probably due to better coatings, but what we really found odd was the background contrast, noticed by Ridwan. For some strange reason, the field of view around the very edges were greyer in the 103ED, then got darker going inward and brighter around the planet.

It’s not unusual to see a bit of light scatter around a planet, but the overall contrast did not appear as uniform across the entire field of view. We switched eyepiece focal lengths and diagonals to be sure, and it was coming from the scope. No matter what we did, the contrast was not uniform in the 103ED and this was the only telescope in this review that did that. Regardless, we all really enjoyed both these scopes and highly recommend them. During the evaluations, June gave a slight edge to the image in the 103ED because the light through-put was a bit better and even though the contrast was not as uniform across the field, the overall planetary color contrast was still a bit better than the 100ED and we all agreed.

The most astonishing thing though was some of us were still impressed with what appeared to be a slightly sharper image in the 100ED at 200x. Even at this higher magnification, it was a bit sharper than the 103ED at 160x! I was pretty surprised, especially since they both had ample time to cool down. I just can’t help but think what an amazing value these little 100ED’s are. Both of these scopes were fabulous though. Unfortunately I did not bring a different 103ED to the shootout, but I might test them both again.

So far, we have this particular Vixen 103ED, Vixen 100ED and Orion 100ED tied for 1st place and the Antares in 2nd place.


WILLIAM OPTICS FLT110-TEC vs. TELEVUE 102IS

This particular apo from William Optics utilizes an oil/gel spaced triplet lens made by TEC and is housed in an OTA by William Optics. We had a few other OTA 's set up on this particular evening. One was a Televue 102IS, Televue NP101 and a TSA102 from Takahashi. The first target was the Trapezium in Orion's nebula. From my location, there’s quite a bit of light pollution and I'm limited to about magnitude 4.5 naked eye visibility, but as I stated before, the seeing was excellent. The FLT110-TEC has a bit more light grasp than the other scopes but there’s a twist to this, so hang tight. The first time I looked through this instrument, I knew this comparison was elevated to another level. The contrast was stunning and we could resolve six stars in the trapezium as clean, little airy discs with no junk around them at 143x. Ridwan wasn’t able to see the E and F components at first, but once he was shown a diagram
from Burnham’s Celestial Handbook, he immediately saw them. Most observers will tell you that it makes a difference when you train your eyes where to look.

Next, we fired the Televue 102IS at the trapezium using magnifications of 125x and 176x. Although we could still discern the E and F components, none of us were as impressed with the image as the stars trickled in and out of focus. In other words, the airy discs did not appear to be as pronounced in the TV102IS. On a more scrutinized level, there was noticibly less light concentrated in them and a bit more scattered outside. The contrast was also not nearly as striking as it was in the FLT110-TEC and everyone agreed.

The four brighter components revealed airy discs in the TV102IS, but they were still not as defined as they were in the FLT110-TEC and it was obvious that it was not caused by the slight differences in aperture, but more so, the actual optical quality. Most of the stars energy should be concentrated into that airy disc. We used various magnifications in both instruments and the results were conclusive. BTW, the airy disc and fainter, ill-defined rings in the FLT110-TEC appeared text book perfect!

We then fired both scopes at Saturn and once again, the FLT110-TEC clearly prevailed. It revealed a sharper image overall and a staggering 20% more contrast than the TV102 in our apparent visual estimation. This was obvious while observing the subtle, but darker belts on Saturn, as well as the rings. The TV102 looked softer in comparison. This was unquestionably a direct result of the scattered light we noticed around the airy disc during the in-focus star test. In case you are curious to know, the TV102IS did exhibit some minor false color on Saturn while it was harder to detect in the FLT110-TEC.

This now pushed the FLT110-TEC into 1st place, with the Vixen 103ED, Vixen 100ED and Orion 100ED in 2nd place, the TV102IS in 3rd place and the Antares 4" F-15 in 4th place.

Now I realize that some of you may be shocked to see the TV102IS behind the 100ED scopes, but there is no bias in this review. We called it like we saw it and I'm sure that had I tested another TV102, the results probably would have been better. I've actually tested other TV102's that were actually better than this particular one, but we did not have them for testing side by side at the time.

WILLIAM OPTICS FLT110-TEC vs. TELEVUE NP101

Next, It was time to compare Televue’s flagship NP101 to the FLT110-TEC. During our tests, the color correction on brighter stars was a tad better in the NP101 but once again, the in-focus star test was slightly superior in the FLT110-TEC. The NP101 produced an airy disc which was surrounded by less light scatter than the TV102, but still more than the FLT110-TEC. We then fired both scopes at the Trapezium using 154x in the NP101 and 143x in the FLT110-TEC. We could see all six stars in both scopes but once again, the contrast was still noticeably superior in the FLT110-TEC. I seriously began to wonder if we even had anything that was better than this incredible optic from TEC and I can definitely say it is one of the finest 4” apochromats I’ve ever tested and Ridwan had a keeper since it belonged to him.

We then compared Saturn in both scopes. The NP101 was magnified 154x while the FLT was at 205x and 143x. Over all, the contrast and picture was still superior in the FLT110-TEC again! The surface features simply stood out more clearly and the background was darker and prettier to all of us. When we examined the edge of the rings, the hard and defined outlines were a bit more evident in the FLT110-TEC. You may own an NP101 and see that the edge of Saturn’s rings look really sharp, but remember that everything is relative. When you’re comparing scopes side by side at this level, you would understand. This particular NP101 that belongs to June exibits a tad of over-correction while the FLT110-TEC exhibited a tad of under-correction.

So far, our test results kept the FLT110-TEC in 1st place, with the NP101 in 2nd place, while the rest were pushed into third, fourth and so on.

TELEVUE NP101 vs. TELEVUE 101

This particular review was conducted when Jupiter was visible at a different time from the rest of these comparisons. We’ll get back to the other scopes again but let’s compare these two Televue refractors first. To this day, some observers ask about how these two Televue's compare. The NP101 is the latest version, which is supposed to have improved glass and it does in fact have a shorter physical dimension, but the focal length, 540mm's remains the same.

During careful testing using Jupiter as the primary target, the images in the older TV101 were actually a tad better in contrast when compared to the newer NP101. This occurred after a side by side with two different NP101’s in particular at 216x and 154x. The contrast just seemed a bit better in the older TV101 no matter how the tests were done, even after we had switched diagonals an eyepieces to be sure, but it was still pretty close.

As it stands, we had the FLT-110-TEC in 1st place, with the (very close) TV101 and NP101 in 2nd place and so on.

Televue 101 vs. TAKAHASHI FSQ106 “Q”

Now I realize this review is about comparing planets and stars at high magnification, but you've gotta see the star fields in these scopes in order to appreciate how good they really are with long, wide field eyepieces. The wide field vistas are beautiful. The Takahashi “Q” is a 530mm tank that packs a punch but in reality, this scope is more of an astrograph even though can use it visually, but it's really overkill. There were two units I tested. The first one Ridwan and I star tested was for Markus Ludes of APM telescopes before sending it to Germany. It exibited just a bit of under-correction while the second unit exibited just a bit of over-correction. The issue here as that this is an extremely sophisticated optical system for visual observations, and it's quite temperature sensative. The pictures taken with these scopes are sensational and Televue's NP101 and TV101 are very nice in this area as well.

The NP101, TV101 and the Takahashi “Q” are all, four element designs. Ridwan and myself made some very careful visual comparisons with the “Q” using my own, personal TV101 on the Double cluster in Perseus with a 22mm Panoptic and a 20mm XW. We were surprised at how close the image quality was, including the edge sharpness and we even switch out eyepieces since there are slight differences with the. In all, they were pretty kneck and kneck. Both Ridwan and myself could see that the contrast in the “Q” was slightly better. It wasn’t much but it was there. It amazes me how Televue and Takahashi make 4 elements scopes this good.

I saw one of the most memorable views of Saturn ever with the little “Q”. The seeing was absolutely breathtaking at home and I set my Televue Binovue up with it using a pair of 19mm Panoptics and a 3.8x barlow. Although this only produced 106x, the image was amazing, and to see Saturn floating in space with all this glorious space around it, it was something I’ll just never forget! That night I spent three hours on and off just staring at it and invited two neighbors over to see how beautiful it looked. I could hardly pry them from the bino. They’d never seen anything like it before. I’m sure the TV101 would have produced a beautiful image as well that night but it was on a different occasion.

If you are considering either of these scopes, the Televue has a more narrow tube assembly because it uses flocking instead of baffles like the Q. The Q on the other hand is extremely short but it's like a little Sherman tank and it's pretty heavy. For visual applications, there's less need for such sophisticated optics and the more simple the optics are, the more well behaved they usually are under climate change.

As it currently stands, we have the FLT110-TEC in 1st place, with the FSQ Q, TV101 and NP101 all pretty close in 2nd place and so on.

WILLIAM OPTICS FLT110-TEC vs. WILLIAM OPTICS FLT110-TMB

Now this would be an interesting comparison. Once again, the FLT110-TMB is an air spaced triplet, designed by TMB, but the optics are by William Optics. I had second thoughts about how I was going to present this particular refractor because there were four problems right from the go. I think people should know that I wasn’t going to share this at first but read on.

The first problem occurred when my crew and I first examined the optic on the William Optics FLT110-TMB. I will try and post photos. It’s not at all unusual to see a little bit of dust inside of the inner optic when a refractor is new, but this optic was nothing like that. The entire inner optic was caked with dust as if it had literally been sitting on an optical bench for weeks on end and was just put into the OTA. I asked the guys to look at it and they were stunned at how caked the dust was.

The second problem was the 2” to 1.25” visual adapter that came with the OTA. There was so much slop when it was placed in the focuser, we could actually jiggle it inside. Although we didn;t use it, we still checked it. Understand that William Optics has a very smart and unique tapered design on the barrels of their adapters, but there was still something wrong here. The third issue was the focuser, which kept slipping back when the tube was pointed upwards. Whenever we tightened the tension screw, it would prevent it from slipping, but would not allow us to adjust focus upward. I realize that there are some other screws which require some tools to adjust it, but I have to ask myself, for a $2800 OTA, why wasn’t this already done at the factory and what about all the other inconsistencies?

The next and worst problem of them all was the optic itself. It had been cooling for three hours while we evaluated the other refractors. There was so much spherical aberration outside of focus, it stayed all night long. When the scope was pointed at Saturn, we could see a nasty glow around the planet and something was surely wrong and it wasn’t the dust but more so, the severe aberrations in the star test. The in-focus star test revealed a very tiny airy disc with lots of scattered light all around it. This is what happens to the airy disc when alot of the light is not concentrated in it. This was a case of major spherical aberration. I decided to notify William Optics about the problems.

I wanted to give them a chance to fix the issues because I felt it was the right thing to do before presenting this review and I even told them I was using it for a review. After explaining the problems with William Optics, I was told that I would receive a new and proper OTA that would be inspected. We finally got the second unit in for testing and inspected it. The first thing I checked for was the dust inside and once again, it was caked with it, just like the first one but in various other parts of the glass inside. I'll post pictures of this one too. The new 2” to 1.25” adapter fit better though and the focuser was adjusted properly but then came the worst. We set the scope out to cool for two full hours and once again, it had a severe amount of under-correction, so much in fact, that the images were very soft at higher magnifications of around 180x to 200x and I could see that nasty glow around Saturn again. At this point, it was like bringing
a pocket knife to a gun fight when comparing it to the FLT110-TEC. It’s quite possible that the spacing of the optics was the culprit. I brought this issue up with William Yang in New York at the North Eastern Astronomical Forum, better known as NEAF. He explained that improper spacing of the elements was most likely the cause.

I’m not here to bash anyone, but I gave William Optics the opportunity to replace the first scope and even said it was for my review, and in my opinion, they were given a fair opportunity to correct it. I will let you now that out of every scope that was tested in this review, the FLT110-TMB was the least favorable. The optics in both FLT110-TMB’s were unacceptable and should never have even left the factory this way, especially at $2800. I love the fantastic TEC model we tested though, which sadly is no longer available.

We still have the FLT110-TEC in 1st place , the FSQ, TV101, NP101 in 2nd place, the Vixen 103, 100ED, Orion 100ED in 3rd place, TV102IS in 4th place, Antares in 5th place and the FLT110-TMB in last place.

WILLIAM OPTICS MEGREZ-110 (Indipendant test)

The Megrez 110 is a doublet apo from WO with a focal ratio of F-5.95. This new refractor wasn't actually part of this review until recently, when I had an opportunity to test it. A friend of mine had indicated that he actually had a Meade 80ED that was consistantly outperfroming it on the planets and he couldn't understand why. After acquiring the Megrez to test it myself in order to find out, I noticed that it was a bit out of collimation, but the biggest problem were zones, due to rough surface polishing and there was also some false red color, which is another story. This, combined with major spherical aberration really put me off. This was the third William Optics refractor for this review with diplorable optics. Getting these scopes serviced was also quite a challenge. This scope was placed last with the FLT110-TMB.

WILLIAM OPTICS FLT110-TEC vs. TAKAHASHI TSA102

It was time to compare the fantastic FLT110-TEC against Takahashi’s flagship 4”, the TSA102. The focal length is 816mm, which is almost identical to its FS102 predecessor at 820mm’s. The TSA102 utilizes an air spaced triplet with top of the line glass, also called FPL-53. The star test in our unit was real impressive at 233x on Procyon. The in focus star revealed a perfect airy disc, with a few faint and ill-defined rings around it, which trickled in an out a bit with the very slight fluctuations in the atmosphere. It was a beautiful sight and absolutely textbook. The seeing was fantastic and one of the most memorable sights was Sirius at low magnification in the TSA102. It literally looked like a brilliant, light blue diamond on a perfectly uniform back ground without a trace of false color!

We then fired both scopes at the Trapezium in Orion. Right from the get go, we knew that this comparison was elevated to an unprecedented level of performance. All six stars in the trapezium were clearly visible TSA102 and the contrast was absolutely breathtaking in comparison to the other scopes! Even Ridwan was beside himself and I was scratching my head. It was pulling out the faintest stars and the in-focus color correction was flawless at 164x.I immediately went over to the FLT110-TEC and altered the magnifications from 143x to 204x and was absolutely astonished that even as good as it was, the contrast in the Tak was even better by an incredible 10% to 15% in our visual estimation. I suggested we switch out the diagonals for fun. June compared the two scopes in silence new the outcome.

We then pointed both scopes at Saturn. Once again, we were all beside ourselves! At 233x, the image in the Tak was easily just as bright but, there was a hardness to it like no other and it was crystal clear, without a trace of false color. You have to remember that the FLT110-TEC had beaten every single scope up to this point, so it was quite astonishing to see. Ridwan was so impressed with the TSA102, he literally sold his the wonderful FLT110-TEC just two days later, before we could even complete the comparison and purchased his very own TSA102. You had to be there to truly understand what we were all going through on the incredible night. It was like watching the greatest boxing match in history! Dispite the fact that I’ve tested countless 4” apochromats, I can honestly say that I’ve never encountered anything quite like the TSA102. It simply amazes me that an optic can be made this well.

This now easily put the TSA102 in 1st place and the incredible FLT110-TEC into 2nd position and so on.

TAKAHASHI TSA102 vs. TAKAHASHI TSA102

It was time to compare the best of the best. Ridwan decided to bring his new TSA102 over for visual testing. We had two of every Pentax XW eyepiece for the comparison. We decided to test the two scopes on Rigel, side by side at 166x and 233x. We were all surprised to see how different the star tests were. In the original TSA, there was just a hair of under correction and to our amazement with Ridwan’s, there appeared to be savere over correction in his model. Something was definitely wrong and I knew this was not at all typical of Takahashi! Both under correction and over correction are forms of spherical aberration but over-correction is worse. As the optic acclimates, it can either stay or move further and further away from proper spherical correction. It’s better for an optic to be slightly under-corrected because it will usually improve as it acclimates closer to ambient temperature.

We then decided to compress the rings around the airy disc and there was a noticeable difference. The two rings around the airy disc in Ridwan’s TSA looked heavier and the airy disc was noticibly smaller from light not being as concentrated in it. We then fired both telescopes at Saturn and the results were conclusive. The contrast was much better in the original TSA102. In Ridwan’s TSA, we could see some scattered light around Saturn and it didn’t look as sharp. This was obviously a direct result of what we saw during the star test. I know how great the quality control is with Takahashi. Most of the Takahashi's I've tested are absolutely wonderful scopes, so anything could have happened here and as I stated before, things can occur with the best brands. The unit was immediately returned for a new one without any hassles at all. I would also like to say something about how Art at TNR deals with these situations. If he even hears anything like this, the first words out of his mouth are, send it back! Art can't stand the idea that any of his scopes are not working correctly and that's the best thing one can do. This now put one of the TSA'a at the back of the line.

TAKAHASHI TSA102 vs. TAKAHASHI TSA102 PART II

We now had a new TSA unit in our possession and made another comparison. Right from the get go, we could see that the new unit was fantastic! Both telescopes performed beautifully and we decided to keep comparing the two. I looked at June and Ridwan and said well? Everyone agreed that the images were practically identical but with a very slight edge going to the original TSA but still, both were absolutely nothing short of sensational and were clearly superior to the other scopes we tested no doubt. I know anybody would have been happy with either of the optical units. We then aquired a fourth TSA102 from a friend of mine name Chris Woodell. Once again, I was utterly impressed and it had just a hair of undercorrection when acclimated. Absolutely state of the art apos!

TAKAHASHI TSA102 vs. TAKAHASHI FS102

It was now time to compare the TSA102 to my favorite 4” apochromat of all time, the Takahashi FS102 and BTW, I also love the FC100. The FS102 has a fantastic reputation. There were a couple of interesting things we noticed between these telescopes when we compared them side by side. First, the overall background contrast was practically indistinguishable in both telescopes while viewing Saturn. The only difference noticible about the TSA and the FS was that the FS had a tiny bit of false color on some brighter stars and the images were just a tad bit warmer. Regardless of these comments, the TSA102 and the FS102 were pretty much neck an neck.

The FS102's incredibly low price of around $1500 to $1700 on the used market is an absolute bargain but most of all, they are the most consistent refractors I’ve ever tested and unfortunately I’ve lost count of how many that is. The fact that they are doublets, makes them very temperature friendly and they are very light weight, making them easy to mount. The winner? Read on......

TAKAHASHI FS102 vs. Televue NP101 (Daytime test)

Many people have asked how these two differ in day light. I'll never forget the day we spent during an afternoon with some friends comparing these two scope using some XW's in both scopes. High magnifications are not required but the main thing we wanted to see is the differences in warmth. People have often advocated that the FS102's are just a tad warm but you never realize how cold it is until you compare it to the NP101. Every single observer that was there that day didn't even question which scope was which. The Televue is actually warmer by quite a margin in daylight. Sharpness appeared the same at these magnifications but the color contrast accurracy on objects goes to the FS102 and everyone agreed.

NP101 vs. VIXEN 100ED (Temperature acclimating test)

Don't draw any conclusions until you read this whole paragraph. None of us will ever forget this night. Remember, now that the ED100 is a doublet and the NP101 is a four element design. While viewing Saturn with June's NP101, a friend of ours named Kelvin brought his Vixen 100ED to the Topanga observing site. When we all started viewing Saturn in both scopes, everyone aggreed that the 100ED was winning hands down because it was noticably sharper. The image of Saturn was flaring in the NP101 right on axis. This is a symtom of cool down. I told June it's most likely not cooled enough, but Kelvin enjoyed the better view in his Vixen 100ED at least another hour until the NP101 finally stabalized and it was all over. Everything about the NP101 was nicer but it just comes to show how long it takes doublets and multi element designs like the NP101 to start working at full thrust.

TAKAHASHI FS102 vs. FC100

If you want to put your stars on a diet, then get either one of these. Many observers have asked to have these two compared and this is something I made a point to do for you. The main difference between the FS102 and the FC100 from an optical aspect is mainly the placement of the flourite element. In the case of the FS102, the element resides at the front while on the FC, it resides "behind" the front element. The decision to go with the flourite element up front in the later FS model had more to do with optical coating applications and this is obvious when looking at the coatings on each OTA. In the FS, the coatings looks dark, while the FC looks somewhat thinner. Is there a visual difference? Yes, but they are very similar and I’ve actually compared them on several occasions and this is all I could notice.

In one particular case about seven years ago, my buddy Jim M. and I were viewing Jupiter at Charlton Flats next to Mt. Wilson using a pair of Takahashi 5mm LE eyepieces and Vernonscope diagonals. I’ll never forget being so frustrated with my FS102 this night. The seeing was so stable that I could actually see the slight pulsations from the stepper motors in my Losmandy GM8 mount. Jim had an old Vixen Super Polaris mount for his FC and it was tracking as smooth as a whip! At approximately 165x in both scopes, the images were just a tad sharper in the FC and I looked at Jim and suggested we exchange diagonals and still, the image was a tad sharper in his FC and both of us could see it.

Eventually I said this has got to be coming from the stepper motors in my GM8, so we turned the drive off and I watched the planet drift across and through the axis. When this happened, I immediately went over to the FC and looked into the eyepiece and still, it was still a tad sharper! No matter what we did with exchanging the eyepieces and diagonals, the FC prevailed just slightly. Another noticeable difference between the two though was the actual color of the belts on Jupiter. They looked just a tad more vibrant or pronounced in the FS and I liked this better. This probably happened because of the coatings in the FS, I really don't know. I highly doubt most observers would have been able to detect much difference between these OTA’s unless they had the conditions we had to allow it. Both scopes are fantastic and there are probably slight differences in all of them. We’re talking about A+, A and A-. That’s still extremely excellent either way you slice it.

Since all these OTA’s are so consistent, I would take this comparison with grain of salt because most of the nights I’ve compared them, the differences were not even worth noting.

TAKAHASHI TSA102 vs. TMB102 vs. TMB115

All these scopes are triplets. While attending NEAF in 2007, I noticed that Markus Ludes had a TMB102 and an TMB115 on his table. I acquired both units and couldn’t wait to test them. Both came in the exact same size tubes except one optic is bigger than the other. I realize this is supposed to be a comparison between 4" scopes but I thought I’d share my experience with the TMB115 and the TMB102. I allowed both OTA's plenty of time to settle down. After comparing the two units, I actually liked the planetary views better in the TMB102. It just wasn’t as good as the 102 and it showed. Upon inspection of the star test in the TMB115, I noticed some very slight zones and this revealed itself on the planets as well. The contrast was just not quite as good.

This comparison between the original TSA102 and the TMB102 will forever remain engraved in my memory because even before we compared them, I had spent a good amount of time star testing the TMB102 and viewing planets with it and I knew it was an absolute gem! June and I conducted this next comparison ourselves. We used a set of Pentax XW eyepieces and both scopes went head to head. To our astonishment! with both OTA’s trained on Jupiter, neither June or myself could possibly distinguish any difference at all between the two. We switched diagonals and eyepieces and the contrast, brightness and sharpness were literally identical. To be honest with you, I don't really focus on what kind of glass any of these scopes use. I just test them visually and call it like I see it but according to Tom Trusock, the TMB102 actually uses OK-4 glass, and as I stated before, the TSA102 uses FPL-53 and both were absolutely fantastic! Hands down, these OTA’s represent the pinnacle of the refractor world and in my opinion, you could not find a better 4”, anywhere in the world.

About the only potential drawback to the TMB is that it's quite a tank and it uses a composite tube material that could introduce some tube currents in fast dropping temperatures. Dormant materials like this are fine, but in a closed tube like this, it may not be the best way to go in certain climates. At no time however, was this an issue during my tests at sea level.

When this review was completed, I boxed the orginal TSA102 back up and I kept it for someone I thought would really appreciate it and until presenting this review, he has no idea he owns it. About two months after this particular shootout was completed, a man asked for my assistance in getting a really great refractor with a mount and all the accessories. The most important thing was that he didn’t nag at all about prices like so many others often do. He was a very humble man, especially since he forked out so much hard earned money. It was for this very reason that I picked him the best 4” I ever saw in my life. The Serial number for this TSA102 is #06121 and now belongs to Tamiji Homma.

THE WINNERS AND TOP PICKS IN THIS SHOOTOUT

1st place - Takahashi TSA102 and TMB102.

2nd place - Takahashi FS102/FC100, WO FLT110-TEC.

3rd place – Takahashi FSQ106 "Q", Televue 101 and Televue NP101.

4th place - Vixen 103ED, Vixen 100ED and Orion 100ED.

5th place – Televue 102IS.

6th place - Antares 4” F-15 achromat.

7th place – Takahashi TSA102, only one unit out of four. William Optics FLT110-TMB, William Optics Megrez 110.

Good seeing!
Daniel Mounsey AKA Doctor D

For Sunshine.
Sep 4, 2008

Some thoughts refractors versus reflectors By daniel mounsey

https://www.astromart.com/articles/article.asp?article_id=790

INTRODUCTION

I decided to put these two high-end telescopes head to head to share some insight that most observers and amateur telescope makers themselves are not even aware of. I seldom sell telescopes and keep most of the ones I acquire, so I have several different types of high-end models to choose from. Most of us know that no telescope is perfect, so having choices obviously makes things easier. So, why would anybody compare a 6" refractor to a 14.5" reflector? The main reason is because each design does something the other one can't do as well. Most observers are quick to adopt the idea that aperture rules, a very foolish statement. This cliché has been passed around forums quite carelessly with little or no regard to the issues that come with aperture. Aperture may rule in some cases, but it doesn't apply to everything in astronomy, and not every top quality telescope is flawless either.

NOTE: Most of the photos I've provided will follow at the end of the article and should be pretty self-explanatory.

REFRACTOR VS. REFLECTOR

These opinions are based on my own hands-on experiences of using both of these telescopes in the field. In my opinion, there are still too many observers who continue to compare these telescopes on the wrong targets. For resolving fine details in globular clusters, galaxies, planetary nebula, selected nebula and smaller open clusters, the 14.5" Starmaster wins hands down. Its greater resolving power simply allows it to excel in these areas of deep sky observation. It can also out-perform any refractor on multiple stars as well as the Moon and planets BUT not without some inherent issues that plague its contrast and sharpness in a major way and I'm not just talking about a boundary layer at the primary or heat currents from the ground. Here, the larger reflector will not appear to perform as consistently as the refractor no matter how good the optics. Some objects will appear to take on a more processed or noisier appearance, while the refractor, although dimmer makes every target appear completely unaltered and pinpoint with stunning contrast.
The refractor will more often than not, surpass the larger reflector on large, extended nebula, extended star clusters, star clouds, multiple stars, and produce wide field vistas of the Milky Way that a larger reflector would be completely unable to compete with. More often than not, larger refractors like the FS152 can also outperform a larger reflector on the Moon & planets more consistently in just about every manner for specific reasons we will discuss. A refractor, simply by its nature has unparalleled contrast that few reflectors could possibly match if their gremlins are not under control and getting them under control is a huge challenge in ways observers never imagined. The learning curve for a reflector is monumental compared to a refractor.

There's also something else that's extremely appealing about a large refractor like the FS152. I'm sure some of you will understand that you get the feeling like you're actually looking through a conventional looking telescope with a tripod, like something you saw in a textbook or classic sci-fi movie when you were a kid. That feeling is something that no dobsonian design can rival. When you are sitting down in a chair, relaxed, using a precision mount, you can really focus and concentrate on what you're viewing. I'm sure many of you could share countless experiences and opinions regarding the attributes of each design but these are just a few to consider.

SO HOW DO YOU KNOW WHAT TELESCOPE YOU SHOULD HAVE?

The simple answer is not to look for absolution in any one telescope, as you will most likely never find it. Just collect as many different telescopes as you can afford, so you can make the choice that best suits your desires at the time. If you don't have enough money, then you will have to learn what questions to ask yourself in order to make the best choice to suit you.

STARMASTER 14.5" HYBRID

Starmaster telescopes are arguably some of the finest dobsonians in the industry. Rick Singmaster is a stickler for optical quality in fact he is quite adamant about making sure his scopes are good before letting them out the door. Part of what has made this easier is Carl Zambuto, who is arguably one of the finest and most consistent mirror makers in the industry in my opinion. This combination of dedication is a wonderful mix. The Starmaster Hybrid is a really fast F-4.3 reflector. Telescopes of this nature will usually benefit from a coma corrector to increase contrast around the outer visual periphery. This will allow stars to appear as points, nearly all the way across the field of view, with minor side effects on axis except for the most demanding purists.
This particular model has goto and uses the latest XP4 Sky Commander DSC for its deep sky navigating and can be updated at any time. The goto drive is practically silent and exclusive to Starmaster. In order to move the telescope manually with your hands for star hopping, you must first make sure both the altitude and azimuth clutches are disengaged. As long as the telescope has been aligned to two stars, the computer will not lose memory on where it's pointing in the sky during this procedure. The clutches can later be reengaged at any time without the need for realignment. The hand paddle has several features which are nice for fast slewing or fine centering of objects. It's pretty nice to have a dobsonian of this aperture with features like this when you realize it tracks as well. You also do most of your observations without any ladders, a big plus.

There are some pros and cons with regard to the Sky Commander XP4. I've been viewing deep sky objects for many years and enjoy observing elusive targets. To me, the database is still very limited when compared to the Argo Navis. For example, let's say you are using a popular book like the Night Sky Observers Guide and you decide to view all the objects in one particular constellation, also known as constellation mopping. Some constellations cannot be completely mopped and you are left to move on to another constellation prematurely.

The Night Sky Observing Guide has an almost inexhaustible object list and yet, there are several catalogues it has that the Sky Commander does not. I wouldn’t mind this so much were it not for the next issue. Even if you enter the RA and DEC coordinates provided by these references, the Sky Commander does not allow you to enter an accurate enough decimal for its declination axis in particular without some careful thought. This proved to be quite debilitating with regard to the accuracy and confidence I had that I found my target. Although you can store and even download a limited number of objects of your choice, I still find the XP4 somewhat limiting for a telescope of this caliber. I suppose the next step will be to use something portable like the Pocket Sky or if you wish to use a computer, you can install the wireless SkiFi that Carina Software now offers.

Once you have found an object of interest with the Sky Commander, you simply press the enter key and press the goto key on the hand control and away it goes. Regardless of some of the cons, this telescope is super user friendly and the drive system is amazingly smooth. The focuser on the Starmaster is beautiful too. It uses the Feather Touch focuser by Starlight Instruments, which have become a favorite among purists these days.

MIRROR CELL

This is something I always check with dobsonians. The mirror cell in the Starmaster is very nice. Metal cable slings have received excellent ratings with regard to edge support but there are a few key features consumers are rarely aware of regarding mirror cells in general. The biggest one is how the edge supports behave, relative to the flotation points that support and move the primary mirror forward and backward while collimating the telescope. An issue I've seen in some competing designs is the use of a sling that does not move in unison with the flotation points. This can cause binding, shifting or pinching of the mirror and even cause the mirror to get hung against the side support pins in some cases, depending on their position. I've even seen where some telescopes have to be pointed vertical to get the primary mirror to drop back down. The Starmaster uses a flotation, edge support but more importantly, the edge support and rear flotation points all move in unison, the way a proper cell should move.

Collimation is held in place quite firmly without the issues of flexure. I placed a laser collimator in the focuser and watched the red dot on the primary to see if it shifted out of the bull’s-eye as I moved the altitude up and down and it stayed centered. This is a common problem not often mentioned in reviews because it either gets overlooked or ignored. This is something I always check in a dob to help verify if it's coming from a lack of strength from the secondary support, the mirror cell or the truss design, etc. Overall, the Hybrid is a solid, little system.
The secondary is adjusted with four thumbscrews that are quite smooth when turning and they hold collimation extremely well. Wood structures in general sometimes have a tendency to expand and contract in various temperatures, so it isn't a bad idea to check collimation a couple of hours into the observing session. For the most part, I'm impressed with the Starmaster in that regard.

OPTICAL PERFORMANCE

The optical performance on deep sky targets with the Starmaster are wonderful and in some cases, quite stunning, especially when you consider that this has a 14.5" mirror. Newbie’s should understand that no matter how well figured mirror is, the coma is inherent in a system this fast. With the coma corrector in place, stars appear like small points on nights of good seeing and their colors shine vividly. We also commonly forget that a good secondary mirror is also a crucial element of the optical train. Don’t under estimate the secondary. During several star tests I conducted, the patterns appeared concentric, clean and practically identical on both sides of focus without any bothersome issues of astigmatism, spherical aberration or common turned edge. To me, it’s just another typical Zambuto. Star clusters like NGC7789 and M11 appear like salt sprinkles with dark backgrounds. Galaxies, planetary nebula and various types of objects shine beautifully through this telescope.

PLANETARY PERFORMANCE AND “YOU” OF ALL THINGS

There's no doubt that Starmaster’s are good planetary telescopes, even with their fast optics. There have been a number of reports of this from the most reputable and well-known observers. But how consistent are these planetary images, really? The Starmaster is not without its issues and it has a major one I'm about to discuss.

One of the biggest oversights regarding not just one, but literally every single ATM who specializes in large dobsonians, is focuser placement. It can destroy everything you’ve paid the extra money to defeat, mainly the quality of the image you get with planets. Just go to the galleries of all the big ATM's and see for yourself what side their focusers are placed on. None of them are on the left hand side of the upper cage assembly. It's as if they all copy each other without any regard to the dire thermal consequences, a HUGE mistake for some planetary enthusiasts!

In order to picture a focuser on the right hand side, imagine standing in front of the telescope looking down the tube. In this case, the focuser would appear on your left. If you were standing behind the telescope looking up the tube, the focuser would then appear to be on the right. An ATM can put the focuser on the left side or right side of the upper cage assembly, but putting one on the right side all the time as every ATM does is like asking a right handed golfer to play with their left hand all the time. This focuser placement has serious side effects with your body currents when using higher magnifications on stars and planets depending on your viewing location.

It stuns me to see how much observers obsess over optics, yet give little or literally no regard to this very serious problem. Imagine all the time and effort put into a finely figured set of mirrors in a wonderfully crafted telescope, only to have the images degraded because of a faulty focuser placement. Just to give you a perspective of the seriousness of the issue, professional observatories that allow public tours, require that all occupants leave by a certain time. Why is this? Because humans are a major source of heat plumes, and domes have to be acclimated so their sensitive cameras can do their work properly. Viewing planets and tight, multiple stars at high magnifications in an amateur telescope are also sensitive in the same way.
Now imagine an open truss tube and you’re savoring every second of the precious seeing to resolve the most spectacular planetary detail and you're standing right next to a completely open optical path and BTW, a typical light shroud will not stop it. This will have profound consequences on the image quality and this can easily be proven. ATM's should always offer focuser placement as an option to the consumer, especially if they are planetary and double star enthusiasts paying thousands of dollars. Unfortunately Starmaster does not offer this option despite several suggestions I've made. I've even discussed the issue for years in forums and have even given talks on the topic at public events.

HERE'S HOW TO PROVE THIS FOR YOURSELF

You can conduct this experiment with an out of focus star using an eyepiece but nothing makes it more obvious than a barlow lens and a binoviewer. This method produces one of the most remarkable and clear pictures of the schlieren or streak test in vivid detail. For this test, do not use any eyepieces with your binoviewer. First, point your telescope on a planet or a really bright star. The Moon itself is too bright in case you're wondering. Center the object carefully, so you can get a clear picture of the secondary spider vane with the illuminated light in the background. Just as an experiment, hold your hand in front of the optical path and you can see your body currents pouring off like fire plumes!

Even if you are using a thick, down glove or jacket, it will not stop these heat plumes from occurring and possibly crossing the open optical path as well. The boundary layer will appear to move slowly, like ripples on a pond in various directions while bad seeing will display itself as a fast, flowing stream in one direction. It's up to you to teach yourself what each movement of air represents. Body currents will usually pour across the field depending on the direction the telescope is pointed “relative to you”. Humans are all a major source of heat, like a furnace. When that heat is exposed to the cold, the difference in temperature is what causes the plumes. Remember those helicopter cameras that the military and police use to catch the bad guys in the dark? They appear as a heat source on their monitor. That's how much heat we give off.

COMPARING THE TAK AND STARMASTER ON JUPITER

During this shootout, my observing buddy John Curry and I put the Takahashi FS152 next to the Starmaster for a shootout. While John observed through the 6" Tak, I observed with the Starmaster on a night of excellent seeing. No matter what magnification we used, more often than not, I was continually getting blurred or softened images in the Starmaster at precisely the same time John was not in the FS152! This occurred over the course of the entire evening. Most observers would probably dismiss this as bad optics, thermal behavior of the primary mirror or various fluctuations in seeing if they didn't know any better.

What’s the problem here? The problem is that YOU are also a major source of the thermal activity. Bigger aperture isn't going to compete with a world-class refractor on double stars and planets if the focuser isn't on the correct side for your viewing location, not to mention the other serious thermal issues reflectors are plagued with already. So, just remember that aperture does not always rule in every case.

John and I both watched while the FS152 continually pulverized the Starmaster on Jupiter, producing consistently tack sharp images with vivid surface detail, a truly beautiful sight! Jupiter's moons were nothing short of sensational, appearing like perfect, tiny, little pin-balls. You could also make out their relative sizes in the FS152 while the Starmaster's were harder to define. Sure, there were a couple of moments where the Starmaster was amazingly tack sharp on Jupiter with vivid colors and surface detail, but they were no where nearly as consistent as the Tak and it's hard to concentrate with distractions like that. Concentration and relaxation are the keys to seeing more detail.

There was one time where we switched scopes and John yelled out that the Starmaster was amazing on Jupiter, then I quickly ran over to get a peek and by the time I saw it, the sharpness was gone. Rarely ever did this happen with the refractor. When I removed the eyepieces from the binoviewer in the refractor to see the thermal behavior, the picture was perfectly clean, no thermals at all! When we compare the mountain of challenges a reflector must face in the field to what a refractor faces, it's literally like comparing an elephant to a flea. Once again, so many things can go wrong with a reflector while practically nothing can go wrong with a refractor. The Starmaster is a very nice dobsonian but the focuser placement is a major blunder for observers on the west coast and a truly frustrating one to say the least.

UNDERSTANDING THE DIRECTION OF YOUR SEEING CONDITIONS AND YOUR FOCUSER POSITION

The focuser placement for my circumstance may not be the same for yours. In order to determine what side the focuser should be on depends on what direction the air moves when your seeing conditions are actually good, and you need to learn that first. Here on the west coast, the on-shore breeze only occurs when the airflow moves from the south-west to the north-east or west to east. Since the planets in North America rise in the east and usually transit towards the south, think about what's happening with a focuser that's positioned on the common, right hand side of the upper cage assembly. The results are a disaster!
Your body is now tragically positioned upwind, relative to the position of the planets you are viewing. This consistent breeze is carrying your body currents directly across the optical path. Now, let's imagine the focuser on the left side of the upper cage. Now your body is positioned downwind and the air will carry your body currents away from the telescope instead of across. Have you ever seen a golfer throw grass in the air so they have a better idea which way the air is moving? The same thing applies to telescopes, it’s no different. The amount of air we are talking about is very subtle in fact sometimes you may even need to dampen or wet your finger and hold it up just to tell which side of your finger the breeze is on. Another way to tell is to light a match and see which way the smoke trails. Remember that it only takes a small amount of air movement to cause a problem

SOLUTIONS

So you ask, why not just rotate the upper cage? Because the focuser board on this Starmaster is angled slightly upward on the right hand side. If you rotate the upper cage so the focuser is on the left side, the focus board is now angled downward along with the finder, not to mention the Sky Commander and clutch system are also on the right hand side of the telescope. Why not rebuild the upper cage? Why not use a special shroud material or an extended light baffle? Why not use a large fan to suck or blow body currents away from the telescope? Well you know what? I have a better solution. Just put the focuser on the correct side of the upper cage and it's done! No more fussing. The rest is counterintuitive and it's a lot of unnecessary work anyway. Telescopes of this caliber should always be made to order, not the other way around. Another issue is fans. Starmaster does not provide you with any primary mirror fans, which speed up the acclimating process in colder temperatures, so be prepared to install your own. This Hybrid has Floyd Blue fans installed with variable speed control and they work excellent. Note that there are no current shrouds included with any telescope on the market that stop body currents.

TAKAHASHI FS152 / EM200 TEMMA II

Oh do I ever love Takahashi. The Japanese are a truly dedicated culture when it comes to their telescopes. There's practically nothing to be desired after owning one of these. It's like owning the finest pocket watch money can buy. Whether it’s an astrograph for shooting the night sky or visual intimacy, it all ends here for me. Takahashi produces my favorite telescopes in the world.
To me, the FS152 is still the finest 6" refractor in the world for visual use. It's also one of the most incredible telescopes I've ever owned, not just because the images have so much contrast, but because they are consistently beautiful. Just set it up and it works every time. No fussing with collimation, thermals, fans, body currents, focuser placements, etc. To this day, given the choice of any 6" refractor currently available, I would still pick this particular model over any other, even if I had to pay more money for it. It has several advantages going for it that most consumers are not aware of. One of those advantages is the fact that the lenses can be taken completely apart, cleaned, put back together again and collimated right at home without any sophisticated equipment. Takahashi has a simple collimator that will help you do the job on your own.

I'm not suggesting you do this but should anything happen to the lenses in a triplet, be ready to pack it up and ship it back for tuning. You will not be working on it yourself if the glass elements shift out of alignment, especially during shipment. Another issue is consistency. I've tested countless triplets and finding an especially good one for planets is like shopping for a straight 2x4 in a stack of lumber. These simple doublets were easier to produce and more forgiving to work with than triplets but don’t get me wrong. A nice triplet can be seriously excellent too.
I've also had this refractor right next to two different world-class 8" triplets from TEC and TMB and about the only differences detected visually, were that the images in the 8's were slightly brighter or larger. Even the 8" owners were stunned. Being that the FS152’s focal length is only 1216mm's means that it's also an F-8. But, what's even better is that it's still a relatively wide field instrument. The stars are crisp and pure across the whole field while viewing with high quality, wide field eyepieces at this focal ratio. It’s also just a fluorite crystal doublet, making it extremely lightweight compared to most triplets and therefore, much easier to mount solidly. You don't have to lug a massive mount around if you want to travel with it. It also acclimates quickly, being a simple doublet with thinner, shallow optical curves. An 8” triplet can take as long as three hours to hit its optimal performance. This particular doublet was star tested after being exposed to a temperature difference of 30 degree F. The immediate star test revealed savere under correction and reached perfect spherical correction in just 65 minutes. That’s fantastic when you consider how much temperature variance it was exposed to.

Another issue I have with triplets is their weird looking appearance when you balance them on the DEC axis. You pay $15,000 to $20,000 dollars for a nice 6” setup and the optical tube assembly looks like it slid backwards in the tube rings. You later realize that this is how they look when they are properly balanced. Some companies offer counter weight tube rings, but once again this adds, more unwanted mass. These are just several advantages the FS152 doublet has over triplets for visual observers. It would be nice if companies came up with a way to offer really simple, high quality doublets like the Takahashi FS and FC series at F-8 for observers who are really into visual observing and even then, some incredibly good astrophotography can still be done.

COLOR CORRECTION HYPE AND CONFUSION

Many observers prematurely obsess over color correction without realizing its place or even worse, without having any actual experience behind an eyepiece with various refractive designs. They read about different glass and all the sudden, they make premature choices. Remember that a camera picks up light differently than the human eye. Cameras saturate light, while the human eye is not as sensitive to colors as a camera.

If you leave a camera exposed long enough using a state of the art apo refractor, it’s still possible to eventually see false color at some point on brighter stars. Sure, you may see a tinge of very minor false color on Vega with the FS152, but just about everything including planets are color free to the human eye most of the time. Another common mistake I read is observers using the edges of the Moon as a guide to revealing false colors. You can do that but you have to be careful. False color can occur even while using a Newtonian with an eyepiece in place. I've seen this many times with my own reflector.

The issue occurs in the air with a color dispersion associated with Earth's atmosphere. Sometimes when objects are being viewed slightly closer to the horizon, you will often see a reddish fringe on the lower side of a planet and a greenish, or bluish fringe on the upper side. An observer could easily mistake this as an issue regarding the telescope’s color correction without even realizing the actual cause. This is the same phenomenon that causes the Sun to still appear on the horizon at sunset, when in actuality, it's already below the horizon. If you are a big double star fan and you're seeing all kinds of atmospheric turbulence and false colors for example, take a #25 red filter and watch what happens.

The FS152 puts planets and stars on a very serious diet and will easily compete with any 6" triplet sold today regardless of price. Sadly, the FS and FC series are no longer in production. This model utilizes a 4" focuser and has some truly fantastic options. In order for it to come to focus, it needs a 3" extension tube. Instead of using this extension tube, the space is occupied by a Moonlite focuser with a fine focus that simply screws on the back of the tube with the aid of a Takahashi adapter. I had no intension of removing the stock focuser because I wanted to preserve its originality and value. Telescopes like these are investments. Another plus is that the FS152 has enough in-travel to allow a completely sealed 2" filter wheel in conjunction with a 2" star diagonal. I can quickly flip through each filter from Broadband, Narrowband and OIII to determine which one provides the best view in seconds!
The EM200 Temma II is another high quality product from Takahashi. I love this mount as much as I love the telescope. It moves with high precision and the polar scope is second to none! As a test one evening, I did a polar alignment. After completing the polar alignment, I took a cross hair reticle eyepiece and pointed the telescope on a star at 215x towards the south and went into the house for 15 minutes to make some coffee and came back outside and it was still dead center, over the cross hair. Sure, there are software programs for polar aligning but it’s still a time consuming process and it’s mainly for photography. I'd just rather polar align and be done.

EM200 TEMMA MYTHS

Some myths have floated on the internet about the EM200 Temma I'd like to clarify. One is that it only runs on 24 volts, which is not true. The fact that you can run the mount on 24 volts simply allows it to slew faster. You can run it on 12 volts, but it will move at half the slew rate, that's all. The only reason I usually run the EM200 at 12 volts is because it draws less current from my battery. I have an AC outlet on my particular battery but have no reason to use it with the converter. Takahashi has now introduced an even newer version of the Temma II which allows it to slew at the faster 700x rate with just 12 volts instead of 24 volts. It also has a few additional improved features.

Another myth is that the EM200 does not have a goto hand control. The EM200 does have a goto hand control but the only difference is that it's optional. There are two hand held DSC computers you can purchase for the EM200 and I use both. The first one is the original Temma II DSC produced by Takahashi. Although it's discontinued, you can still find them floating around on the used market for a few hundred dollars. Sadly, this DSC received a lot of criticism from consumers because of its extremely limited database. It also used yellow LED's instead of red. Maybe the technicians at Tak had a fondness for colors at the time, I don't know.

Even though this computer and the Sky Commander have limited databases, there's one advantage this controller has that most observers overlook. If you’re using the Night Sky Observers Guide for example, you can enter RA and DEC coordinates very accurately for all the obscure catalogs, unlike the Sky Commander which does not allow you to enter in the dec coordinates more accurately. Takahashi also offered a newer, optional, hand held IPAQ with Pocket Sky by Software Bisque but now both hand controls have recently been surpassed by LLC. This company is now offering a controller that has many features and a huge database and will be available November 15th 2010. All you have to do is plug it in, no different than plugging in any other handset on a modern computerized telescope that's already been programmed.

The Pocket Sky by Software Bisque has an optional T point targeting algorithm but I never use it because it's more for permanent installations and it needs a good number of points. The EM200 moves like silk and makes a beautiful sound when slewing. Some observers describe it as a dentist drill, but it's a very pure, high pitch sound. I usually avoid meridian flips and view objects in one constellation over the course of each night. If you like jumping all over the sky, a German EQ mount is not for you.

HOW ARE THE VIEWS IN THE FS152?

Spectacular! Star clouds and Milky Way vistas are a sight to behold! Star clusters look like powdered sugar. For example, NGC7789 under a dark sky with this telescope is the finest image I've seen in any telescope, regardless of aperture. I recall one evening at a large star party using the rare 30mm Leitz widefield eyepiece on the Double Cluster with the FS152. It was the best I’d ever seen it and that eyepiece is a fantastic combination with the telescope. I couldn't take my eyes off this view, in fact there was a 24" dob parked right next to it and most of the observers were still gawking at the views in the 6" Tak even more. You have to remember that everything is relative. If you decide to use a huge telescope, that just means you're going to be viewing smaller, fainter objects on a louder level. The 6" Tak produces tailored quality with darker backgrounds.

I agree that there are many cases where aperture is awesome and you really need it, however, you have to choose your targets wisely and learn to appreciate the advantages and disadvantages of each instrument. I have a pretty good picture of the night sky and I love just about everything I see, even if it's just a single faint star. It’s more about knowing and appreciating what you are looking at. Another vivid image at a different star party was the North American nebula using the original 50mm Axiom from Japan (now discontinued) and the 30mm Leitz with a UHC filter. If you've never seen this, you have no idea what you're missing. It practically looks like a picture. You can literally see the Central American region and all the hard outlines around North America. This is one of nature’s greatest spectacles! There is so much to be said for wide field views of targets like the M24 star cloud, M35, M44, M45 etc. Double stars consistently look textbook perfect with tiny airy discs that resemble miniature pin-balls at high magnification under good seeing.

CONCLUSIONS

Every dob owner should have a refractor and every refractor owner should have a dob. To disregard either design is a closed minded approach to the hobby as far as I’m concerned. The Starmaster is a beautiful telescope in almost every regard, but the focuser position is absolutely frustrating to no end and huge blunder for any ATM. Most planetary observers know that a Starmaster will kill any refractor when the thermals are not an issue, but the fact that the design is not a consistent performer at higher magnification because of it will remain an issue for me and probably for many others who are unaware of the actual problem. Of course this will depend on your observing location.

The Takahashi leaves me with little or nothing to be desired regarding the targets it's intended for and it's practically immune to thermals. That in itself makes it an extremely efficient optical system, even if it is just 6". It's a pleasure having both telescopes together. They each have their attributes. The EM200 mount is amazing too and in my opinion, still, the finest mount in its class. If I had to live with one though, I'd pick the 6" Takahashi system. It combines the accuracy I need for double stars and the comfort of sitting down compared to the bigger dob and the image quality is absolutely smashing! Reflectors are still king for planets and still my favorite choice, but there's a lot more to a reflector than just size. Execution of the design is paramount and the Starmaster Hybrid would still need to carry some of the same modifications as Ed Grissom's spectacular planetary Newtonians. I’ve never seen anything that could rival Grissom’s designs and it's not as simple as most observers think.

Steady skies,
Daniel Mounsey
aka Dr. D

Shanghai Clear Outside

Snow in Shanghai

Flood in Dandong

Two satellite pictures from NASA:

One Year Ago

Present