Hey guys, I have been trying my hand at shooting star trails, but I'm having a problem. I am using a SL1 and an opteka fish eye lense. At f11 and Iso set to 100, I have been setting my camera to bulb and leaving it open for a while. However, for some reason any shot over 15-20 minutes won't work. Once I release the shutter, the image doesn't appear. Instead there is a bracketed number on the lower right of my screen that just blinks and blinks. It's usually a 4 digit number. Any ideas as to what that bracketed number means and what I could be doing wrong? Thanks guys!