Quote:
Originally Posted by raymo
Mine doesn't seem to Kevin. Logically, why should it? you double the
exposure but cut the amplification in half, ending up with approx. the same result.[other than noise difference].
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That amplification creates noise which limits faint details. Get that lower and the limiting factor is sky fog.
I did a test with my Pentax a couple of years ago on M42. The low ISO longer time won over higher ISO shorter time. Then I did a test with different ISO's but same time. The higher ISO had more gain but about the same proportional noise increase. As long as the exposure wasn't black clipped, the ISO didn't matter much. Time was the greatest factor in limiting magnitude.
Of course this is Pentax but I also found the same thing with my old Nikon. Canon may be different. I don't have one of those to try.
