While planning this shot, I didn't find as much info as I would of liked as far as astro stuff with the Samyang / Rokinon fisheye, so I figured I would post an example of what worked for me. This pic was taken with a 25-second exposure at ISO 2000 with an E-PM2. I bumped up the exposure, contrast and clarity in LR, and added a small amount of sharpening and noise reduction. I went with this shot because of the meteor visible at about the one o'clock position of the frame. The math calls for a 30 second exposure, but in my case I liked 25 seconds (and even 20) better. As this was my first attempt at this sort of thing, I wonder if the shorter exposure worked because I was in a truly remote area- just outside the Strawberry Mountain Wilderness in Eastern Oregon last week while bowhunting.