keybaud Posted December 26, 2013 Share Posted December 26, 2013 Having read about Gina's issues with back focus in this thread, http://stargazerslounge.com/topic/198330-ginas-esprit-80ed-pro-unboxing-and-first-impressions/?hl=%20gina, are there any rules, guidance or pit falls I need to be aware of before choosing a telescope to use with a DSLR? I've tried searching but back focus has the word focus in, which appears to be in every thread on here.I assumed it would be better putting this sort of query in this section instead of the Getting Started with Imaging sub-forum, but apologies if it should have gone there. Link to comment Share on other sites More sharing options...
wxsatuser Posted December 26, 2013 Share Posted December 26, 2013 All I know is back focus with a SW 80ED Pro+reducer is no problem, just attach the camera to the reducer with a 48mm T ring. Link to comment Share on other sites More sharing options...
cantab Posted December 26, 2013 Share Posted December 26, 2013 Regarding the forum, just put the phrase in quotes, "back focus", and it should search just for that. Link to comment Share on other sites More sharing options...
baggywrinkle Posted December 26, 2013 Share Posted December 26, 2013 I used my Canon 650D on a my SW80ED, no reducer and it worked fine, could achieve focus very easily. Link to comment Share on other sites More sharing options...
Alien 13 Posted December 26, 2013 Share Posted December 26, 2013 Refractors generally have lots of backfocus to allow for the use of a diagonal, once the diagonal is removed it is often necesary to use a 2" piece to get focus with a DSLR with a reasonable amount of eyepiece tube extension.When using a field flattener/reducer things get more difficult the back focus from the flattener is normally only enough for a T adapter and DSLR and maybe 1 or 2 1mm spacers, the real problem is when using a ccd filter assembly. Link to comment Share on other sites More sharing options...
keybaud Posted December 26, 2013 Author Share Posted December 26, 2013 Regarding the forum, just put the phrase in quotes, "back focus", and it should search just for that.Ah, haa. Thank you. Link to comment Share on other sites More sharing options...
keybaud Posted December 26, 2013 Author Share Posted December 26, 2013 The best description of back focus and how to mange it that I've found on Google was this post:http://www.televue.com/engine/TV3b_page.asp?id=85#.UrxFocaYZaQ Link to comment Share on other sites More sharing options...
keybaud Posted December 26, 2013 Author Share Posted December 26, 2013 The best description of back focus and how to mange it that I've found on Google was this post:http://www.televue.com/engine/TV3b_page.asp?id=85#.UrxFocaYZaQKey points in this post via wikipedia, on these forums, for DSLR users:http://stargazerslounge.com/topic/38049-back-focus-distance-for-dslr-lenses/#entry387208Systems with short flange-to-film distances include Canon's FD (42.00 mm) and EF mounts (44.00 mm), Konica's AR (40.70 mm), and Olympus's Four Thirds System (38.67 mm). These can readily take many other brands of lens.Systems with larger flange-to-film distances include Nikon's F-mount (46.50 mm), Olympus's OM mount (46.00 mm), and the Pentax K mount/M42 (45.46 mm) universal thread mount. These lenses can be adapted to many camera bodies. Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.