|Shutter speed: 1/320|
My good Facebook pal Jon Levi helped me figure that out. It seems that the Sony HVL-F58AM explicitly says that shorter exposure times than 1/200 will create this effect, since the shutter on DSLRs is NOT digital but still works with "curtains" as shown in this explanation:
As you can see in the photo above the "black bar" is actually the frame without the flash hitting anything and the rest in this case is a bit overexposed bit where the flash hit. You can use that for artistic purposes, but probably not a lot of uses for that.
To work around this issue, my flash has an HSS mode. However, though this mode was on when I was shooting, it didn't work for two reasons. One, it doesn't work in flash manual mode, only in TTL which I don't use. Two, I was using my radio flash controller, and HSS requires that the flash be on the camera itself. This strengthens my case for a new and improved flash setup for Sony. Sony wants to be this innovator to win some high end camera market share against Canon and Nikon? This is definitely one ares that could do with a complete overhaul. Sony should totally rethink how people use flash photography and make cheaper ones that are a generation ahead of the competition, perhaps borrow a page out of the Steve Jobs Apple playbook.
Sony, if you are listening I have tons of ideas that could put you well ahead of the competition. Also, I wouldn't mind living in Japan for a while (hint hint).
Update: It seems that some of the issues might be specifically with that A99 model as seen here:
Thankfully I don't need a lot of higher than 1/200 flash photos and I can use low ISO settings to keep the iris open instead of fast shutter.