So I am a bit confused here. I know that there are some super long tele-lenses out there for multiple mounts, as well as telescopes you can mount a camera on (through various means). Are the f-stops and focal lengths directly comparable, or do they have some other bit that means that comparisons will be off? Just seeing these shots that look amazing, and wanting to start getting into it a bit, but trying to find a great "starter" deal to make sure I like it before investing. I understand that f-stops dictate exposure times. Telescopes tend to be faster, so as to lessen exposure time, lessening star drift? Or it is easier/cheaper to make a fast telescope as it can be a mirror lens design, and the donut bokeh never gets seen? I guess what I am asking is what are the benefits to each, and how you would do a comparison as far as FoV and exposure times between the two. Is it just like comparing lenses?