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Re: [APML] saturn occ. time exp.



I'd suggest that you plan to use a high total focal length for this. Eyepiece projection is one way if you have the projection tubes. At short focal lengths you will be mis-matched on your exposures. Either the moon will be over-exposed or Sat will be under-exposed. High magnification at long fl's will get the two objects close to correct exposures. If you can design your system to get you 1/2 to 1 sec exposures that will be best. Use the hat-trick for your shutter to minimize vibrations For your instrument, an 16-18mm eyepiece with a 120mm projection distance will calculate at 1/2 sec exposure for a 200 speed film; 1 second for 100 speed film.  
Bobby Middleton 
 
 

"To think that the eye could evolve by natural
selection seems I freely confess absurd in the
highest possible degree"    CHARLES DARWIN
http://www.koyote.com/users/bobm/astro1.htm
----- Original Message -----
From: Marios
Sent: Thursday, November 01, 2001 7:08 AM
Subject: [APML] saturn occ. time exp.

Hi friends,
 
I would like some advises for time exposures for the Saturn Occultaion on the 3rd of November (this Saturday)
 
I will be shooting Prime Focus with an 8" f/5 F1000 Newtonian telescope. I will mount the camera on the 2" focuser.
Shall I use a fast film (800 ISO?) or a slower? What would be the time exposures?
 
Thank you.
 
Marios.