Yes this is a really scary problem when you don't know what it is. My theory is that it is an electromagnetic (wifi-like) interference: shooting at different shutter speeds hepls to avoid the vertical sync of the interfering signal. I had this problem in environments with camera surveillance, heavy wiring and electric systems. I thought my 7D was broken too, but it kept happening in the same places. What a nightmare when you're on a client's place!
Yes this is a really scary problem when you don't know what it is. My theory is that it is an electromagnetic (wifi-like) interference: shooting at different shutter speeds hepls to avoid the vertical sync of the interfering signal. I had this problem in environments with camera surveillance, heavy wiring and electric systems. I thought my 7D was broken too, but it kept happening in the same places. What a nightmare when you're on a client's place!
TiCasque100 2 weeks ago