Hi All,
I posted this at s.a.a. recently but have had only deafening silence so far.
Any help or comments on this appreciated. I'm thinking of modifying my GS 8 inch f/6 dob to use a binoviewer.
I want to avoid the need for a barlow, compensator, OCS etc, so plan to move the secondary & focuser back by the typical focuser in-travel requirement (110-130mm, S&T March 2005 p98), say 4.5 inches, and maybe use an extension tube for one-eyed viewing.
Punching the numbers into Newt V2.5, this results in no vignetting with my current 51mm secondary.
Some questions:
- Is this a dumb idea?!
- When using a binoviewer without a compensator or barlow, does the bino itself change the magnification at all? In particular, the Burgess Optical binoviewer? See
http://www.astromart.com/articles/ar...article_id=180
- The cited mentions an ep focal length of around 20mm before noticeable vignetting with the Burgess 1.25 binoviewer with 18.5mm clear aperture - sound about right? Interestingly, at the moment they're for US$199 with a free pair of 17mm WA eps.
- Any other thoughts on binoviewing with a newt? (I guess I want to avoid if possible the $ and optical flaws of the Denk combo of BV+OCS+Power Switch, S&T March 2005 p92, i.e. image vignetting and off-axis distortions with power switch).
- Anyone had experience with the Saxon binoviewer (AU$399, e.g.
http://www.andrewscom.com.au) ?
Thanks!
Mark (Blue Mountains)