I have started to develop astrocompare.com because I wanted a tool to compare two different sets of exposure settings for deep-sky astrophotography.
There was no tool available to tell me in relative terms how many times more or less light a given setup will collect compared to another.
The MVP for astrocompare.com which I have created is a calculator in which you can input: ISO, shutter speed & aperture as well as a number of frames for two exposures and it tells you how much brighter one is compared to another:
