That seems maybe a teensy bit drastic (though it clearly depends on your
eyes). I regularly use my 35 pano in my F4 SN. Maybe the exact number is
personal though (for my it might be 8).
Pete
Jamie Dillon wrote:
> There's that very handy rule of thumb, multiply your f/ratio by 7, and don't
> mess with an eyepiece with a longer focal length than that number. I just
> remind myself to avoid the kidney-beaning. Yes this has to do with exit
> pupil, just a simple way to work the equation. Dickinson and Dyer bring the
> x7 bit up in the new version of The Backyard Astronomer's Guide. Invaluable
> book.
>
> Once I got a free 40mm Plossl from Discovery scopes. In my 11" f/4.5 the
> kidney-beaning was impressive.
>
>
>
---
Aug 25, 2008: TAC Web Page Updated http://observers.org/TAC.cgi/Announcements/
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Received on Wed Aug 27 13:36:43 2008
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