Pros: Excellent image, high contrast, works very well visually, comes complete with storage case.
Cons: Expensive, Definitely not "Entry Level", Odd price breaks
The Bottom Line: The Televue 102 is ideal telescope for the very serious and dedicated visual observer, and is the sort of scope you buy once in your lifetime.
Pirich's Full Review: Televue TV102 (x250) (250 x 102mm) Telescope
The Televue 102mm refractor (or TV 102) is what many people have come to see as a "Perfect" telescope, and for good reason. It is a combination of size, performance, and quality which has become a standard among high end telescopes. The TV 102 is actually a family of different telescopes available with various options. My review will center on what this product is, what it does, and how it performs compared to alternatives. My review is divided up into these sections:
Telescope Series Explanation
Background
Description and Usage
Comparisons with Alternatives
Conclusions
Telescope Series Explanation
The TV 102 is actually a single telescope system with a front end optical set, tube, and focuser which appears in three different versions. The versions range from a bare minimum optical tube for an advanced amateur all the way up to an optical masterwork of brass on a beautiful ash wood tripod ready for a CEO's corner office.
The lowest cost and most basic version is $2200.00 with the TeleVue ivory tube (sort of an antique white color in person) seen here:
http://www.adorama.com/TV102.html
This is the telescope sold "Slick" with only the optical tube and the carrying case. This version has no eyepiece, diagonal, mount, tube rings, or other accessories needed to turn this into something you can observe with. If someone is an advanced observer with a stable of scopes and mounts, then this is the version which doesn't result in a cabinet filling up with extra parts and eyepieces. The case has punched out spots in the foam ready to take on these components for making up a kit.
The next step up is sold with the minimum equipment to do something with the telescope "Out of the box" for $2,635.00:
http://www.adorama.com/TV102C.html
This version has the ivory white optical tube and hard case like the last version, but now includes the tube ring needed to attach it to a mount as well as a diagonal and an eyepiece. This version still assumes the user has a telescope mount. Again, it is an advanced amateur who will be able to assemble telescope systems this way- the astronomy equivalent of assembling an engine and transmission in a custom car.
The third version is the one in the photograph for this review, which is the TV 102 made with a beautiful polished brass tube on the TeleVue Gibraltar ash tripod with an elegant push mount for $3,175.00. The listing on Adorama has the wrong photo, but is listed here:
http://www.adorama.com/TV102R.html
This is a flagship telescope for TeleVue, and has been titled the Renaissance. This is optically the exact same telescope as the first two versions, and the optical tube has the same accesories as the second version. However, it comes with the Gibraltar wood tripod and visual observing mount, so this version has everything needed to start observing together as a kit. Interestingly, though this version has the brass tube, if you add up what it would cost to buy version 2 and then buy the Gibraltar mount ($595.00, http://www.adorama.com/TVGAM.html), you would have spent slightly more to put the plain ivory powder coat tube on this mount, so this version is actually very cost effective, and even more so if you would like to have a beautiful telescope to have on display in your home since the striking brass tube is essentially thrown in for free (If you see one in person you will appreciate how remarkably beautiful they are).
Background
Refracting telescopes focus light to make an image by using lenses to bend the light by refraction. Other designs such as Newtonians, Schmidt Cassegrains, or Maksutovs all use mirrors to do the work of taking a stream of light and focusing it to a point. The lens and the mirror are fundamentally different from each other: A lens bends light by its frequency, meaning violet, blue, green, yellow, orange, and red colors of light all come to separate focus points (think of a lens as a series of concetric prisms made into rings). The reflecting designs have a fundamental advantage since mirrors reflect all colors of light to converge at the same focus. As a result, all refracting telescopes have an optical flaw where images of objects will have a colored edge or false color from light not coming to the same focal point. All reflecting telescopes are free from this defect, but can have others such as the effects from secondary mirrors in their optical tubes, which make the unobstructed design of the refractor desirable.
To overcome the false color problem, achromatic and apochromatic refracting telescopes have been developed with compound lenses to lessen this effect. An Achromatic telescope has a compound lens at the front made with one piece of plate glass and one from lead crystal. Since these two kinds of glass have different refractive properties, pairing them allows the designer to make a telescope behave as if it had a lens with more forgiving color separation properties and improve the image. However, this is more and more difficult as the telescope's focal length gets shorter, which is what allows it to see wide angles at high brightness. Achromatic telescopes show more and more false color as the designs try to make the focal length shorter.
Telescopes are light amplifiers- compare the area of the front end, 102mm across, to your eye's pupil, approximately 7mm across to see how much more light is coming in. This amplified light can either be used make large dim objects like nebulas (which are often on the order of the size of the full moon) visible with low magnification and high brightness, or make small bright objects like planets larger. As magnification goes up, the image becomes dimmer. Since the magnification is dependent on the focal length of the telescope divided by the focal length of the eyepiece you are using (and eyepieces are useful from 40 mm to 4 mm) in , the higher the scope's focal length, the higher the magnification it has to operate at.
The one number which will tell everything about a telescope's performance is its focal length divided by the diameter, which tells how much it will magnify versus amplifying brightness. A focal ratio of f/15 means the focal length is 15 times the diameter, and the optical performance is equivalent to a camera lens set at f/15 since images are relatively dim. At the other end, an f/5 telescope shows three times the width of field of view and has images three times as bright as the f/15 with the same diameter and eyepiece. The difference is the f/5 needs to bend light much more strongly to do this, and for a refractor this causes false color to be a bigger problem.
As a result, achromatic telescopes need to be f/12 and up to have apparently color free images. Shorter focal lengths have color issues, and observers either have to make themselves happy with this, or use filters to make the purple and blue haloes around objects invisible.
Apochromatic refractors (APOs) are advanced systems with exotic materials such as calcium fluorite used in their lenses to make better color correction at lower focal ratios than achromatic telescopes can. This is expensive to do, and as a result the APO is the most expensive telescope design for any given size. Theu came into their own starting around 1979 when they became available to the public for the first time. Al Nagler, the founder and main force at TeleVue is one of the pioneers of this design and has now made several generations of apochromatic refractors. The TeleVue scopes have built a reputation for superb construction and optical excellence, and unlike other makes such as Astro-Physics who have waiting lists currently 5-6 years long, a TeleVue can be yours tomorrow.
The TeleVue product line goes from small scopes at 60mm all the way up to a 127mm (5 inch) scope. Unlike Takahashi and Astro-Physics, which have both made photography a main focus of their development, TeleVue has always catered to the magical experience of direct visual observation. Though their telescopes have produced outstanding photos, TeleVue easily has the most complete set of visual accessories and eyepieces of any high end manufacturer.
A lot of different variations on refractor designs are in production today, and there are large amounts of discussion about what a real apochromatic telescope is. What the discussion hinges in is levels of color correction. There are those who claim any refractor with two lenses in its objective cannot be an APO. However, in my own experience, the image from an APO is obviously different from any other make of telescope, regardless of its design details. The image of an APO is remarkably sharp and high in contrast, stars are razor sharp pinpoints, and false color is negligible.
The TV 102 is what is called an APO "Doublet" with two lenses in its objective. There are several different designs of high end refractors being made today, and anyone looking at the TV 102 has probably noticed TeleVue makes a telescope with a 101mm diameter called the NP 101, at a price of over a thousand dollars more. What is going on here is the more expensive telescope has a four lens design called a Petzval. The NP101 has a shorter focal ratio and is ready to attach to a camera, where the TV 102 needs another optical accessory called a field flattener to attach a camera. Other telescope designs from companies like Astro Physics and and Stellarvue have three lenses in the front end in what is called a "Triplet." What all of this is about is designers have to choose a compromise to meet a design goal. Doublets work well arounf f/8 and keep costs down, especially for visual instruments. Triplets are general purpose telescopes with outstanding correction at focal ratios as short as f/6. Petzval and other four lens systems are intended to get to very short focal lengths, especially when the ability to expand the image across a 6X7 film camera is desired.
Description and Usage
The TV-102 is simplicity incarnate. The tube goes on the mount, you unscrew the dust cap (Personally, I can't stand screw-on dust caps- I am paranoid about cross-threading them. This is probably a hold-over from my day job, though), and then you slide out the glare/dew shield. This part is felt lined to make it slide freely and present a dark surface. From living on the gulf coast, these aren't long enough to prevent fogging on a hight of serious dew, but if you are somewhere with less extreme humidity, it is easily big enough. The focuser is just a rack and pinion, but a very nice and buttery smooth one. Tele Vue doesn't inflict set screws on astronomers- nice compression rings grab and hold on to the diagonal and other accessories.
The lengh of the tube is long enough I find it easy to get pointed to an object with a low power eyepiece. A nice thing about a focal ratio as low as this scope's is the field of view is wide enough to do this. Above a focal length of about 1000mm, this becomes nearly impossible, and yet it is the best way to get the scope pointed at "That thing I see there." Tele Vue encourages this with their red dot finders, which are like a miniature fighterplane heads up display which projects a red dot as if you had a laser dot on a point in the sky. The odd thing about this is this visual exploration friendly telescope is combined with a price tag which virtually guarantees those who would find that most useful won't be using one of these.
The TeleVue 102 is at a focal ratio of f/8.6, and the resulting focal length of 880mm is a better compromise for allowing eyepieces to reach this telescope's magnification potential. The image from a TV 102 is very very sharp. Something unusual about an APO telescope is how the image seems to pop out in a fullness which many advanced users can only describe as "Magic."
This comes to the crux of the matter with APO telescopes; the money will go further in other designs, but nothing can outperform them at the same diameter. In the case of the TV 102, the image is crisp from edge to edge in the eyepiece. As a result of this performance, TeleVue actually makes special eyepieces to the tune of $400 each with extremely wide apparent fields of view to exploit their telescope's capabilities.
Comparisons with Alternatives
The TV 102 has very good performance, but there are some caveats. I find instruments like these very difficult to review due to their high cost compared to capability. Sort of like if you review a $100,000 super sports car and conclude it has first rate performance- at that price, it had better! Where in a less expensive telescope, it is easy to resolve the focus of its design, something as expensive as a TV-102 MUST have outstanding performance over a wide range of parameters to justify itself. If you are looking for the most performance you could have bought for $2200, you could have bought several optical tubes, sat an 8" Schmidt Cassegrain like the old Celestron C-8 scopes will outperform this one on total brightness and on planets. You could still get a 10" f/5 dobsonian and an 80mm ED scope to have wide angle and dim galaxies and nebulas all taken care of, and at that point, every trick the TV-102 has would be taken over by a specialist for less money.
The Tele Vue 102 actually does a pretty good job in all of these telescopes' home territory. Mind you, the 80mm scope may get a wider view, the Newtonian can illuminate far dimmer objects, and the C8 will give a sharper view on planets (which is itself odd since the C8 was originally designed to be a general purpose telescope). However, none of these will quite cover the range of the TV-102 with such sharp views. What makes this difficult for me to is this is no longer a case of a compromise to get something with a range of ability but excelling at nothing for less money than buying a family of specialty instruments. This is a compromise bought at the full cost of the family of specialty instruments. So, it clearly does not sound rational, and so it is hard to explain why this product and a half dozen other manufactuers' equivalents prosper in the marketplace.
What I can say is you have to look through one to understand. The image in one of these telescopes is compelling in a way which is difficult to put words to. Perhaps the best example I can give is from hearing an old Victrola wind-up acoustic record player. The sound was not loud like a modern stereo, and there was static. Yet, the sound had a certain reality to it as though I were hearing the real musicians and not a recording. And that is the quality the APO has which brings seasoned observers to see it as a worthwhile investment.
These telescopes bring stars to pinpoints across the field of view, give sharp images of planets, and compelling images of nebulas. Many other telescopes can outperform them in raw image firepower. And yet, the APO's image is renowned for being crisp and clear. And it may be that the simple reason for this is the attention these get as the most expensive telescopes in their size. After spending a lot of time looking through a lot of telescopes, APOs start to stand out as just having very nice and sharp images. And for the money, they should.
Between the NexStar 8 GPS I reviewed earlier (optically it is a keeper), I have had a chance to look through several of the TV-102s. The NexStar flat out wins on high detail and going to higher magnification- and it should, it is twice the diameter of this telescope. But where the TV-102 shines is it can back off in power and still give a beautiful image, where the NexStar can only back down to a 1280 mm focal length witht he focal reducer, so it can't get the wide angle of the TV102. On the other hand, if you take a smaller C5 (either by weight or dollar, perhaps the best value in a telescope), the TV-102 gives an image which looks slightly sharper, and slightly dimmer. These are very different telescopes, and to be honest, though the TV-102 has a pretty image, I'm keeping the C5.
What I am getting at is the APO has lots of alternatives. It stands on the strength of beautiful images, first class workmanship, and solid designs. They are beutifully made, and you can be assured what shows up when you buy one will be ready to go. The Tele Vue TV-102 is made to last a lifetime. These, like the old Alvan Clarks, are destined to be handed down. But out here in Tucson, I have seen a showroom with fully functional 30 year old C8s.
Conclusions
The TV-102 does what it promises, and it does it very well. It is beautifully made, and it is made to be used. But keep in mind it is a bit like a Rolex watch- if you just want to tell the time, you can get something more accurate for less money. If you are new to amateur astronomy, I can't responsibly recommend this as a starter. It's a lot of money when you don't really have to spend much to get started. Do some observing, look through some different scopes, and maybe you will decide you like visual observing and an APO is what you are looking for.
Personally, I find myself drawn to want to like Tele Vue scopes. They are very well designed, and they work well. The reason these exist is so you can get the best. Other brands such as Takahashis, Celestrons, Meades, and Orions seem to be destined to look like industrial hardware and wind up draped in wires for guidance and photography with trains of hardware; Tele Vue scopes are designed to elegantly set on a simple mount and let someone explore and enjoy the sky. If you are that person, and you know you want the best, the TV-102 is waiting for you.
At Tele Vue, we always try to provide good value in addition to great optical performance. With the Tele Vue-102 we offer the amateur a simpler, less ...More at Adorama
At Tele Vue, we always try to provide good value in addition to great optical performance. With the Tele Vue-102 we offer the amateur a simpler, less ...More at Buy.com Marketplaces
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