If the sky is clear this weekend i might try my first attempt at Prime Focus photography. I have my 35mm MV1 Pentax + T-Adapter + OAG and my LX90 8" F/10.
My queston is, would i need to use a focal reducer to bring it down to F/3.3 or F/6.3 ? Also how long should my exposures be ?, think i'l be using Kodak EKT 200 film.
Many thanks Dave
Edited by davesaunders (09/17/08 03:00 PM)
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Suk Lee
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Reged: 10/07/03
Posts: 4315
Loc: Pleasanton, CA
A reducer to get down to f6.3 is a pretty good idea since f10 is very slow photographically. You'll probably get some vignetting.
f3.3 is probably too aggressive - if I recall correctly the 3.3 has very stringent backfocus requirements (it's primarily intended for CCD imaging -- CCD imagers have a very short flange-to-sensor depth.)
At f6.3 on ISO200 at 1500mm or so focal length you can easily expose 30min+ without skyglow problems.
If you're just starting out, sorting out tracking will be your first challenge so you might try bright objects and short (couple of minute) exposures.
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