Thought I would take some photos of my son's new guitar last night. I used my Cactus V4's to fire off an SB800 set on Manual at varyingstrengths and my Yonguou 460 also set manually. The I used was the Nikkor 50mm. Sometimes I had the room's downlights on and other times I just used the flashes in the darkened room.
Unfortunately, most of my images ended up with a large black line on one edge of the image. See the example below. I had this problem when I first started using a flash and somehow fixed the problem but for the life of me I cannot remember why it happened and how I fixed it.
Can anybody help me identify the problem and tell me how to fix it.