Bashar Markabawi said:
Dear All: I am considering to get wo 102. Anybody has some info about this scope and would it be a good choice for astrophtography? thanks
What is the exact model of the scope you are considering?
http://www.williamoptics.com/telescopes/telescopes_main.php
William Optics has sold quite a few telescopes over the years but currently does not seem to be offering a 102mm scope. The only 102mm I can think of was the Megrez 102SV ED.
If this is the scope, I do not believe it is well suited for Astrophotography. This is one of at least four apparently identical 102mm F/7 doublets ED doublets, the Astro Tech AT 102ED, the Orion 102ED, the Stellar-Vue SV-102ED and the WO Megrez 102SV ED. I happen to have the Astro Tech version which I reviewed for CN.
These doublets are based on H-FK61 ED glass which has a Abbe number about 82, similar to the first generation ED glass FPL-51. Given the 102mm aperture and the F/7 focal ratio, this gives quite reasonable color correction for visual use but it not well suited for astrophotography because of the wider spectrum captured by both film and CCDs.
For Astrophotogray, one needed either a better 102mm scope, probably best a triplet if one can afford it. Otherwise an 80mm F/7 doublet based on FPL-53 would be a better choice, the difference would be significantly better color correction at the expense of a slightly smaller (20%) image scale. I have seen lots of great photos taken with 80mm ~F/7 scopes like the Orion ED-80.
Jon Isaacs
