Can anyone explain this blue banding?

[Jeremy Hughes]

I'm wondering if anyone else has seen this blue banding I got yesterday in some of my shots. I've searched a lot and can't find anything specific to what happened. It never happened to me before either. It looks like an aqua watercolor spilled over the footage.

Take a look at these 2 shots for what I'm talking about. 1 was lit daylight with a 1200 par and Kinos. The other all tungsten. I shot with the L series 24-105 and ISO was 320 in both. I was also using typical CP settings like described on Prolost
http://dl.dropbox.com/u/916328/7d_banding.jpg

[Bruce Foreman]

That is "moire", an interference pattern caused by an interaction between "texture" and lighting/camera angle. Several possible "cures" are changing the lighting angle some, changing the camera angle.

You might use a wider aperture for more shallow depth of field along with a slight camera position/angle change so the "offending surface" is not in the same plane of sharp focus as the subject.

You'll also occasionally see this on brick walls, tiled roofs, and other surfaces with some texture.

[Jeremy Hughes]

Thanks Bruce. I've gotten moire before but never seen it look like this. Gotta love that codec :)

[Phillip Palacios]

It's not the codec, it's the line skipping the camera uses to downres to 1080.

[Jeremy Hughes]

Line skipping caused the blue overlayed areas here?

[Aaron Almquist]

Canon DSLR's use line skipping as a means to "downres" the image to 1920/1080. As a result of line-skipping the DSLR basically has to guess where lines are. When it can't quite get it right you get the blue banding and moire patterns.

[Jeremy Hughes]

Now I gotcha. I've seen the stair stepping and moire before but I managed to not have to experience the color banding and never realized it was a possibility. Thanks for the help guys!