So. I do a lot of low-light shooting. I'm a night person. Between my 5dII and my 80mm f/1.2, I'm getting really close to being able to shoot as I've always dreamed of: able to capture the night just as I see it. Tripods: sometimes. Flashes: seldom.





But here's my issue. Even when there's sufficient light to be shooting wide open @ iso6400 in terms of exposure, autofocus is wont to disappoint me me. Often, it will fail entirely, and with so little light manual focus can be roulette. I've got a speedlite--the 430ex-- and I often find myself attaching it just to use the AF assist beam, no flash. I've gotten some amazing shots that way.





But often, portability is a concern for me. It seems silly to lug around a flash for the assist beam. Here's what I want to know:


Is there a dedicated, small active AF device which attaches to the hot-shoe? I've looked all over to no avail.





If not, could one hack one together? Is the communication language between unit and camera proprietary, in need of advanced reverse engineering? Or is it simple enough?





Whatta you folks know? And is there a reason this isn't on the market? Some flaw I don't see? With the amazing low-light capacity of cameras today I can't imagine I am alone in my focus-woes.