Re: [APML] Equivalent ISO of an ST10E CCD

[Jerry Lodriguss <jml@astropix.com>]

>Well, however long it takes is how long it will take <g>. OK I do not
>know this because this depends on the brightness of the object, the
>f-ratio of the scope and the QE of the CCD. This is akin to asking how
>long an exposure on film which will produce the hump in the middle. At
>any rate, the hump in the middle is not the best. Presuming noise
>remians sonewhat controlled, the hump to the right has better SNR
>provided you are not saturating (clipping).


Hi Loke.

I'm sorry, but the question I asked was straightforward enough. For film, 
the answer is not "however long it takes is how long it will take".

If I put a gray card in the sun and I know the film speed and f/ratio, I 
can tell you exactly how long the exposure would be to put the spike in the 
histogram at level 128.

The brightness of the object is defined as a gray card in the sun, the 
f/ratio of the scope is whatever you want it to be, just pick an f/ratio, 
and the QE of the CCD is for the ST10E. Isn't that known?

The hump in the middle IS the best because it is the DEFINITION of what I 
am looking for: the exposure that will put the hump in the middle.

Jeez. I'm getting frustrated.<G>


Jerry
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