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Impressions of the TeleVue 102



Background Information

I have been actively involved in amateur astronomy since I was 12 years old. I am 32 now and during that time I have owned a wide variety of telescopes. Recently, I have been in a consolidation mode and now have whittled my scope collection down to two excellent (if not complimentary) instruments:

· StarMaster 10EL w/a Carl Zambuto primary mirror.
· TeleVue 102 APO refractor.

The TV102 replaces an excellent Vixen VX102FL Fluorite doublet refractor that I recently sold to a friend. If you are anything like my wife, you will ask why I am replacing one 4'' refractor (VX102FL) with another (the TV102), especially since the Vixen has a Fluorite element. Let me first say that I will always own a 4'' APO. These instruments give decent planetary views, are easy to carry, and there is little time spent waiting for the OTA to cool down. In addition, I felt that the Vixen, on a Great Polaris mount with counterweight, was a chore to get outside. The TV102 on a walnut Gibraltar, altazimuth mount is one piece out the door. I really wanted a "grab and go" setup and briefly considered the TV85 on a Telepod mount. But as the saying goes, aperture wins…

Initial Impressions

This scope was purchased new on 10/9/2000 from Anacortes Telescope and Wildbird in Anacortes, Washington, USA. There were several serial numbers in which to choose from and I ended up with #1025. The scope was shipped to me via UPS 2nd Day Air and it arrived along with the aforementioned walnut Gibraltar mount on 10/11/2000.

Included with the TV102 is a fantastic foam lined hard case and, well, not much else. Missing are a finder, diagonal, and mounting rings. TeleVue has positioned the TV102 in the market as a second scope... an instrument to be used by a seasoned astronomer who may already own a diagonal, finder, and mounting rings. Interestingly the price of the TV102 is within US $150 of the venerable TV85.

The build quality is excellent. The OTA is coated with a white "crackle" coating that seems to be quite durable. The focuser is VERY smooth and is identical to the one used on the other TeleVue scopes. Unscrewing the dust cap and extending the dew shield reveals an objective lens and coatings that are stunningly beautiful. The exterior lens of the doublet is coated a very deep green, while the interior lens is coated a deep magenta. One thing to note is that the objective cell is not user collimatable. You must send the scope back to TeleVue if it ever needs collimation. Peering into the tube reveals absolutely no baffles. The interior wall is coated with a flat black flocking material that handles all stray light. This design works quite well. Even when looking at a nearly full moon, the sky background is quite black with little or no light scatter. Overall, the elegance of this scope is in the simplicity of its design… certainly a departure from the TeleVue 101, Renaissance and the Genesis SDF.

First Light

First light for the TV102 occurred on 10/13/2000. My club, The York County Astronomical Society of York PA had a public starwatch scheduled at our observatory. I set up of the TV102 next to the club's A-P Starfire 102 and my StarMaster 10EL.

I plopped my 35 Panoptic into the TV102. Nice, very nice even… pinpoint stars right to the edge. The Double Cluster in Perseus had never looked better. I then panned to M31. The Andromeda galaxy and its two satellites (M32 and M110) were all in the same fov. This was indeed a sight to behold. I then swung the scope over to M13, which was getting low in the west. Some individual stars were resolved to the core but, as expected, the view in the Starmaster was superior in every way.

With the scope having cooled sufficiently, I decided to perform a star test. For an eyepiece I chose a 6mm Radian and also a TeleVue 2X Barlow giving me 293X. When star testing 4'' scopes I always try to get as close to 300X as possible. At 300X, I find that the results are sufficiently accurate without dimming the diffraction image beyond recognition.

I then swung the scope around and focused on Polaris. This is an excellent star to use as a test object. It is sufficiently bright at 2nd magnitude, and it tends not to move very much. With Polaris in the center of the fov, I slowly I racked the image inside then outside of focus. What I saw was troubling. The scope had a sharp, well-defined diffraction pattern on either side of focus, but it was not completely circular…it exhibited a slight triangular shape! Perhaps pinched optics?

The next day I arranged to have the scope tested inside in a lab environment using an artificial star. These tests only confirmed the results of the prior night's star test. There was something wrong with the optics of the TV102.

In any event, I emailed Herb York at Anacortes explaining the problems and the methodology used to reproduce them in a controlled laboratory environment. Herb made arrangements with Al Nagler to have the scoped shipped directly to TeleVue if I was agreeable. I agreed and the next business day I had the telescope shipped to TeleVue in Suffern, New York. Two days later I spoke to David Nagler who explained that the scope had been re-collimated and did very well in tests performed at the factory.

Second Light

I pointed the scope at Polaris and held my breath…Well, I must say that the diffraction pattern is now a perfectly concentric circle and virtually identical on either side of focus. There is absolutely no trace of the pinched optics/collimation problem that I noted above. Using a green filter, I would estimate that scope is corrected to approximately 1/8 wave. Actually in a subsequent conversation, David Nagler stated that my particular sample of the TV102 was corrected "in the neighborhood of 1/7 to 1/8 wave". Anyway, I am relieved that TeleVue was able to correct the problem.

I must say that the scope does quite well on the planets and the moon. On nights of good seeing the TV102 really takes power well. The contrast is amazing…definitely better then the Vixen I previously owned. The Cassini division is especially well defined. Even in moderate seeing this feature is absolutely unmistakable and velvety black. Detail on Jupiter does not disappoint either. Banding is evident from pole to pole in moments of atmospheric steadiness.

Bottom Line

I am quite happy with this telescope. As I stated previously, I will always own a 4''APO. It is the perfect compliment to my 10'' Dob and is one piece out the door. It's an ideal instrument for those nights when I only have a limited time to observe. In fact, along with my Starbound observing chair and my set of Radians I cannot think of a better way to spend an evening.



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