Quote:
Originally Posted by glend
I have just finished some test subs of M8 taken at various Gain settings and durations. As Ray has indicated you can sort of take your pick as far as settings are concerned. I was playing around with Dunk's '3X' rule and it worked out pretty well. First I did a 60" sub at Gain 139 as a baseline, then a 120" sub at Gain 100, then a 180" sub at Gain 50. I was watching the histogram in SGP as they downloaded and was able to see that the best of the three seemed to be the Gain 100, 120" sub which exhibited the best fine detail for the exposure length.
I brought them into Photoshop CC and did a couple of things to them to bring out the fine detail: an auto tone, shadow/ highlight adjustment, nothing extreme, and I did exactly the same thing to each one.
I have attached small versions below for your amusement. From left to right, they are: the Gain 50, 180" version, the Gain 100, 120" version, and the Gain 139 60 sec version.
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Thanks Glen. the problem with trying to evaluate the performance by looking at individual subs is that you miss out on the effects of stacking. For example, for a total exposure of 3 minutes, you will have just the single 180"@50 sub, but you will get three 60@139 subs in the same period. If you want to really compare apples with apples, you would need to stack the three 60@139 subs and compare the result with the single 180@50 sub. And then you would need to somehow stretch the two images so that the background noise looked the same in each - could be done, but not easy.
edit: just looked again - the subs are all pretty heavily black clipped - did you deliberately do that in Photoshop, or perhaps you need a larger offset?