Tuesday, September 10, 2013

Review of the Tele Vue 76 or What are the benefits of a small, portable Refractor?

As I have indicated recently I have very much enjoyed my views through the Tele Vue 76 and it’s capacity as a birding/nature photography scope (and air shows!) but more importantly, it’s go-anywhere size makes it the ideal buddy to take out on a moment notice. This logic doesn't just apply to the TV76, it applies to any and all small, quality refractors. Built like a tank. How many times have you heard that phrase about this class of telescope? It harkens from the Tele Vue Pronto days that has been the hallmark of the small Tele Vue refractor lineup. Heavy duty in a small package. Structurally these scopes are truly overbuilt with buttery smooth focusers, sliding dew shield, accessory clamshell and a powder coated white tube. I did not opt for a green tube.

Optics, build and accessories

My ’76 is actually a used one, not new and is slightly older than the current crop with a different eyepiece holder and it doesn’t have the satin body, it has the older machined shiny body. If anything, I would like to swap out the eyepiece holder as the newer version is an upgrade with dual screws, not one. But the one I have is still sufficient as it too is a compression ring style. It’s tank-like build is sometimes criticized as it’s Achilles heel because it is generally heavier than it’s birding counterparts, but when compared to larger telescopes, it really isn’t that much of a pain. Still birders will prefer rubber bodied, waterproof, gas charged spotting scope in exchange for the views because, you guessed it, the ’76 is not a waterproof scope and as a conventional refractor in terms of structure, focusers are classic rack and pinion with a 2” eyepiece capability that results in mirror reverse images. Birders may prefer the more traditional upright, left to right view. I however, am not one of them. I prefer to keep the image as pure as possible. To keep the tube relatively thin, the scope is not baffled, it is flocked.

Optically this scope is great. But so what. Let’s qualify that statement. Obviously it’s light years ahead of its older sibling, but never mind that. Pronto vs TV76 is a fruitless discussion because they are completely different refractors. Structurally similar, but that’s it. Nothing to talk about there and it has been done to death on Cloudy Nights. However, for buyers looking at used Pronto’s, don’t worry, it’s still a great achromat and worth the investment. Just be careful not to overpay on one because, put simply, you can get great optics from other ED Refractors that are much more modern even though you might sacrifice the build. My 76 exhibits what is typical in an SD doublet (it is assumed that it is in fact FPL-53 but I don’t think it has ever been directly stated) where you will find the in-focus image to exhibit next to little false colour on bright objects. Out of focus images do produce some false colour as expected. Concentric rings are nicely visible and the out of focus image does not indicate any correction issues, astigmatism, collimation problems or rough images. A nicely made lens. If anything, it has been on more than one occasions, been the “gold standard” to judge by in it’s class and only in it’s class not beyond it. The lens is held in collimation with no user adjustment. If it goes out of collimation, it has to go back to the factory. A Starbeam Reflex site as well as a Vixen/Synta finder scope base was added to enhance it’s capabilities with an 8X50 finder scope, although one can argue you might not truly need a finder. The clamshell has been adapted to the ADM 7” Vixen Universal Plate so it is compatible with all Vixen and Synta style saddle plates. It will ride on a variety of mounts like the AZ-4, EQ5 and EQ6.

Working with the Tele Vue 76

Vega Test: Well, I didn’t do one and I don’t really want to do one.

Venus Test: I haven’t done that either. I might one day…

Planets: I have truly enjoyed this scope on Jupiter and Saturn despite the smaller aperture. I have at least detected the Great Red Spot Hollow on more than one occasion, enjoyed tracking transits of the Jovian moons and it is no problem spotting the C Ring and Cassini’s Division. Don’t think I have ever spotted the Encke Gap, but I don’t think I went looking for it in the first place. I’ll have to check next year. I have not seriously looked at Mars though with the ’76 and a review of it pointing out that any f/6 ED doublet APO might not be the ideal “Mars Scope” can be found here at Scopereviews in the UK.

Deep Sky: With just an aperture of three inches, this is going to be relegated to the brighter deep sky objects but there have been plenty of nice views to be had here. None of them are surprising. What I won’t do is compare this to say, a large Dobsonian. This is nonsensical because they aren’t in the same class of instrument. Besides, to state that “a dob blew away the ’76 on faint object X” is more than enough of a statement of “Captain Obvious”. The grandest thing is the wide field. M31 has that galactic feel to it in a dark sky. With a five degree field at maximum, it has been the preferred view at StarFest over much larger instruments with a narrower field. Open clusters like the Beehive, Coat Hanger and Pleiades look like open clusters that you could only fathom in your 8X50 finder scope on larger instruments. The Double Cluster is bordering on glorious in a five degree field. Truly an experience to behold. There is something to be said while taking the whole view in of Orion’s Sword region where M42 reigns supreme. It’s something you have to experience. Reading about it doesn’t do justice. Any quality f/6 doublet ED/APO can do this.

This is not a “Herschel Hunter” nor should it be considered as such. It’s a different approach to the traditional deep sky observing. I would treat the ’76 as a nice supplement to your larger telescope.

Double Stars: This is not my primary telescope for double stars, that is reserved for my larger refractors but views have been rather pleasant in the ’76 especially colour contrasting doubles where the APO optics do help. The focal length of course is short at 480mm so “barlowing up” is required or get some of those high quality, low focal length eyepieces. The scope is capable of operating very well up to 200X. Some of the finer splits have been Porrima, Castor, Rasalgethi (Alpha Herculis) and Rigel (split surprisingly well).

Crossing over to the other side

Crossing over as a multi-function scope is where I think this scope really shines. I actually purchased it for the ability to photograph birds and wildlife on top of the astronomical capabilities already stated. It extended my options to 480mm (760mm crop factor) with the camera and I have been more than satisfied with the results and if you saw my post from Rattray Marsh, you’ll see why. However, one must remember that dealing with a conventional refractor focus is much trickier than the instant auto-focus mode of my 70-200 L. When you do get the focus right, and it takes work, it’s a nice image as seen from my Rattray Marsh post. I have not used the ’76 as much as I would like visually in this capacity, but what I can say it is breathtakingly bright, crisp and virtually false colour free as expected and keeps up with the big kids on the birding scope scene like Swarovski, Leica, etc.

I have been working with the ’76 for some concepts as a terrestrial or landscape imaging telephoto. This is really out of the norm for an astronomical telescope as I have not seen many people attempt it. My 70-200 L is truly my go-to landscape lens but I decided to see what the ’76 could muster. It’s a strange, unique world indeed as these photos indicate. As mentioned in my Rattray post, the Orion Field Flattener is a BIG help here to keep images sharp across the focal plane. It may not be the most efficient scope for this purpose, but it’s fun to tinker and go outside normal boundaries. Canon does make 500mm and 600mm lenses…have you seen the prices? Have a look at some of these concepts.

We established the TV76 as a capable Air Show supplement to existing lenses here

Can you hike it? The simple answer is yes with conditions. The weather has to be fairly nice. The ’76 is a fair weather friend. Weighing in at five pounds, it's bulk in contrast to lighter, rubber-armoured spotting scopes could be an issue but short hikes are reasonable. One must keep in mind that the supporting cast is larger than most spotting scopes depending on what it’s intended for. One must take a robust tripod capable of supporting it well, eyepieces, barlows and a diagonal, camera adapters, field flattener( again I find it useful), and camera bodies. Given that list, it’s clear one must be dedicated to this kind of activity. If doing an overnight backpacking trip is in order, chances are, the ’76 is not your scope. Short hikes, possibly day hikes can be done with the above conditions IF you want to do it.

Some other thoughts

Despite all that has been written, what place does this little refractor have in the era of the (modestly) inexpensive ED/APO doublets from Asia? Well, given it’s price new, the TV76 is a big investment. But what you do get is a capable telescope/terrestrial scope that’s built to last forever, assuming you treat it right. Now, I do have many friends who have invested in small ED/APO doublets imported through SkyWatcher, Explore Scientific, Astro-Tech, etc, and I can say these scopes can deliver as good as or very close to the TV76, optically. They may have not subjected their refractors to the rigors that I have as stated above but I cannot say anything negative about them only positive things which might lead some to wonder why I even bothered to post this at all. My attempt here was to lay out what you can do with a small refractor in this class. There are many debates about the merits of this or that refractor and it’s been done to death. Some say Tele Vue’s quality will last forever. That may be true, but if you treat your telescope well, chances are it will last just as long. Treat it badly and well, you know what happens. There is no real need to debate this anymore except where quality control may be a factor. Tele Vue’s reputation as a fine optical maker cannot be disputed and every unit that leaves the factory is essentially guaranteed to deliver as promised. That reputation in and of itself might sway owners to it.

As a result of the influx of imported doublets, the used value of the ’76 is taking a beating. Units can be purchased for under a thousand USD which was unheard of a few years ago. So it’s a buyers’ market in the used department.

Bottom line is this. The concept of a small, quality ED/APO doublet is indispensable as indicated above as they can go anywhere at a moments notice. Portable and hike-able with some restrictions. If you choose a TV76, the quality, build and endless possibilities...you will be more than happy.

Here is the scope in it's various configurations.

1 comment:

  1. Thank you. I appreciate your candid review. I have a new 76 and fretted over the cost until I had it in hand. I also own a Tak 102 S, nice optics the focuser is less than poor.
    Best regards