I would like to try to take some night photography - specifically the milky way. I do not want star trails, so am limited by the Rule of 500. I have two lenses. A Nikon 35mm f1.8 and a Nikon 10-24mm f3.5-4.5, and am shooting with a Nikon D7000.
Using the rule of 500 and the 1.5 crop factor, I know that the max exposure time I have before I get a star trail is about 9 seconds for the 35mm lens and about 33 seconds for the 10-24mm lens.
What I would really like to know is, is there a graph / chart that I can use to compare or tell me how much light would enter the lens, over the different exposure times, so that I would know what lens would be best to use? Or put another way - would more light enter the 35mm lens at f1.8 over 9 seconds, than would enter the 10-24mm lens at f3.5 over 33 seconds?
I'm going to test both - anyway - but it would be nice to know.
Any advice appreciated.