Re: [APML] Long vs. Stacked Short Exposures

[Wei-Hao Wang <whwang@gmail.com>]

Hi,

As Stuart pointed out, there is a risk of fogging the
film at F2.8 for 40 minutes.  If your sky is so dark
that it allows 40 minutes of exposure, you should 
probably use 40 min instead of two 20 min.  A single
40m exposure will give better S/N than 2x20m 
combined.  On the other hand, if the sky is bright,
of course the better approach is to combine two short
exposures to gain S/N.

Cheers,

Wei-Hao

-- 
________________________________________________________________
Wei-Hao Wang  :)

Institute for Astronomy at University of Hawaii

Address:                       
2680 Woodlawn Drive         Personal Website:
Honolulu, HI 96822             http://www.ifa.hawaii.edu/~wang
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