Weird banding on canon 7d night video

This clip started one night when I was out filming traffic. You can see a dark bar that rolls through the shot from bottom to top. At first it made me freak out a bit, thinking that the camera was somehow broken. I eventually figured out that it is the result of A) a flickering light source and B) the right (wrong) shutter speed. I read somewhere that ideally you should shoot a shutter speed that is double the frame rate. This gives you a 180 degree shutter and it should look very similar to film.

The way that I made these bars appear was by changing the shutter speed away from 1/125 when I was shooting 720p60. I have ideas as to why this creates the banding, but they are all theories.

Moral of the story: keep it at twice the film speed. Change the aperture, or buy a faster lens!
For more 7d tomfoolery, check out http://blog.tinyenormous.com

Category:

Film & Animation

Tags:

• canon 7d
• banding
• night photography
• artifacts
• video glitch

[TiCasque100]

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!