This week I had the chance to test a Takahashi FS102 refractor apochromatic fluorite telescope and also a Celestron NexStar 5SE Schmidt-Cassegrain catadioptric telescope. First one has an aperture of 102mm and second one of 125mm plus a central obstruction. Their light gathering power is similar and also their theoretical resolution. Nevertheless I wanted to check by myself the mythical optical quality of FS102 in contrast to the well-known Celestron.
Tests were made using the same camera to capture video and similar weather conditions both nights. I took in both cases a video of the planet Saturn when reaching the meridian, its maximum altitude. Celestron C5 perform flawlessly because I could get a sharp view of Saturn and its ring at 500x magnification. Takahashi also let me reach that high powers with a crisp result. C5’s focuser is very precise, but Takahashi’s is even more being a rack and pinion system. Focusing the FS 102 was very pleasant due to its smoothness and accuracy. Probably a better contrast in visual images delivered by refractor telescopes also gave it an advantage here.
Trying to resolve fine details, in both telescopes I could see the shadow of Saturn over the rings clearly. Here it is the final picture after applying Registax and Fitswork4 to both videos.
Computer Physics Lab 