So I was taking group pictures for this banquet, and all was going well until my camera started giving me these weird black bands across the bottom of my photos. It started out more like extreme vignetting on just the bottom, but it got worse as time progressed.
I was using an old speedlite 155A from my AE-1 film camera attached to my 30D and I had a Sigma Super in slave mode through an umbrella on the right side. I turned it off by the time I was getting to these photos because I was afraid it was overheating (other people's point & shoots were setting it off full power). Attached are some of the worst pictures. By the 2nd picture, I was already trying to compensate for the black band. When I opened the RAW files in Photoshop and turned up the exposure, it started showing the image under the black band. These were taken on a 30D with the kit lens. Same thing happened with a 28-105mm, but then after about 10 minutes, it was taking pictures fine. I was using a Sandisk Extreme IV 2GB.