Wednesday, December 29, 2021

Televue-85 Finally Arrived

I have rejoined the Televue cult.  Some years back, I owned a Televue Ranger, a semiapochromat that was expensive for a 70mm refractor and wildly outperformed similar sized and more typically priced refractors.

I always regret that I sold it as part of an even then, no longer current view of myself as that poor kid from almost the wrong side of the tracks in Santa Monica.  (It was not quite as fancy back then as it is now.)

The TV-85 is fully apochromatic.   The dual speed focuser is butter smooth at both speeds.  The mounting ring is clever in how it locks the tube while still providing ease of loosening to move the OTA for balance.  Conditions for use were poor, but even the house way off in the distance demonstrated the quality of the optics.  

Everything about this scope is top notch and it weighs eight pounds.  Made in the USA, using Japanese glass.  Another nice touch: ordinary telescopes use a press fit plastic dust cap.  This uses an aluminum dust cap that screws in place.

Will the TV-85 outperform my 5" f/9 refractor?  I doubt it.  The 5" has 49% better resolution (this increases linearly with objective diameter) and more than twice the light gathering power (square of objective diameter). It is also 30% of the weight and far easier to manage.  

It is intended to be a grab-and-go scope: something that goes on a very light mount that you can just pick up and carry outside, or take to star parties without assistance and advance planning.  (This only became an issue after  2014 stroke.  I used to take the 5" refractor and mount by myself to star parties in the Corvette.)

The Explore Scientific Twilight 1 alt-azimuth mount turns out also to be a winner.  Made it China, but try to find a similar mount with slow-motion controls made elsewhere.

UPDATE: As I suspected, looking again at a neighbor's house some distance away with more light, 300x is moving into the fuzzy area although 150x is still pretty darn sharp.  If you have any typical commercial refractor, these numbers for a 3 4" aperture are going to sound absurd.  Astronomical use may tolerate 300x because the contrast of Saturn on a black sky is exquisite and powerful. 

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