I'm doing untracked astrophotography using the 500 rule (seems to work well)......75mm (150mm EFL), comes out to 3.2 seconds per subframe. However I want to do longer exposures without stars streaking. The Sequator software I use offers an option to do 2x2 binning (reducing the resolution from 16 MP to 4 MP). It occurs to me this would also allow me to do 2x longer exposures without star trails since the resolution would be reduced by 2x across each dimension. My question is- is it worth it? Would reducing the resolution like this allow me to capture twice as many stars since I was doubling the shutter speed? If so, I could go even further and create files that were 4x4 binned (going from 16 MP to 1 MP or screen size) and thus make the shutter speed 4x longer or 13 seconds.....would this mean I would capture 4x as many stars? What is the tradeoff?
^that's for untracked photography on a conventional tripod.
Now, since I have the 8 SE I have its mount and I expect that even on this alt az mount I should be able to do a lot better with my camera OMD EM10 II and 75-300 lens? At 75mm how long of an exposure should I be able to do on this mount to get the equivalent of the 500 rule on a conventional tripod? At 300mm? How would I go about mounting this camera on it? Thanks!