This is not a 50Hz/60Hz shutter speed issue! This is a piece of footage that show a chronic flickering problem my 7D is having. It's sporadic so watch closely. I've got the latest firmware. Not sure what this is but I need help. The first piece of footage is color graded and the second is the original footage. I can see the flickering in live view as I'm recording. The camera is set to Manual mode and I'm using a custom "super-flat" color profile.

Please help!

Canon 7D flicker problem on Vimeo

Can you please list all the settings you have on the camera for this shot?

Here is my guess.

Because it seems to occur at or around the time the largest piece of weed or grass hits the center of the frame, I am guessing you still have camera in an auto exposure mode, and that is camera adjusting automatically, and then jumping back.

Sometimes people don't realize there camera is in an auto exposure mode. The 5D for instance will remain in auto exposure if you don't go into the movie set up and select movie settings. IF I recall right, that is same with the 7D ???

My camera was on full manual mode. I think it may be a loose lens adapter, I am using a fotodiox PRO nf-eos adapter and I noticed that as it f-stop reading on the live view screen (although arbitrary because of lack of communication between my camera and nikon manual lens) went to 0 and back to 1.4 just as image was flashing. I reattached the adapter to the lens and then to the camera and it seems to have stopped.

My camera was on full manual mode. I think it may be a loose lens adapter, I am using a fotodiox PRO nf-eos adapter and I noticed that as it f-stop reading on the live view screen (although arbitrary because of lack of communication between my camera and nikon manual lens) went to 0 and back to 1.4 just as image was flashing. I reattached the adapter to the lens and then to the camera and it seems to have stopped.

What I read here is it was in "M" on the mode dial with a shutter speed set and a manual iris setting on the Nikon lens.

What were those setting?

Also,

What was the ISO setting?

The info display flashing that info is a strong clue as to what is going on. That would have only happened though if ISO was in automatic.

1080 24p
shutter speed 50
Nikon 24mm f2.8 @ f4
ISO 200
GENUS fader ND filter
highlight priority mode
CineStyle color profile

But I do think it was the lens adapter, since I secured it the problem has not come back. Although there is no camera/lens communication because of the fully manual nikon lens, the fotodiox adapter has some copper tabs on it that close some electronic loop for the camera. an example is that in photo (not video) mode, when manually focusing with the nikon, the camera give a "beep" along with a small icon flash in the viewfinder that lets you know you're in focus on whatever's in the "box". This was not possible with the cheaper adapter I previously had. So my guess is that if the adapter has some play in it those connections can short on and off, like a loose light bulb.

I apologize if I'm not using the right terminology here.

Donnie - does your lens adapter have a focus confirmation chip? If so, then this is probably the issue. I have a Fotodiox M42 to EOS adapter and had to remove the chip in order to stop intermittent exposure problems while shooting video.

Good luck!

IF I recall right, that is same with the 7D ???

No, that's wrong. On both the 5D and 7D cameras you just select "M" on the main dial. No need to delve into menu settings.