Exposure problem while rolling

[Elieabihatem]

Hello!!

I have noticed a problem while shooting with my 5d mark iii yesterday, i have some exposure problem during the rolling process.
With no light changes during the roll you feel like the image shift -2stop smoothly then go up 2 stops, like you are playing with the iris ring going from 2.8 to 4/5.6 then to 2/1.4

Shutter speed 1/50
Lens 70-200mm canon
Samyang 35 mm and 85 mm
Iris 2.8
Iso 160
25fps
1920/1080p

Can anybody explain to me why this can happen?
Thanks,
E

[RobertTheFat]

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@Elieabihatem wrote:
Hello!!

I have noticed a problem while shooting with my 5d mark iii yesterday, i have some exposure problem during the rolling process.
With no light changes during the roll you feel like the image shift -2stop smoothly then go up 2 stops, like you are playing with the iris ring going from 2.8 to 4/5.6 then to 2/1.4

Shutter speed 1/50
Lens 70-200mm canon
Samyang 35 mm and 85 mm
Iris 2.8
Iso 160
25fps
1920/1080p

Can anybody explain to me why this can happen?
Thanks,
E

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Not sure what you mean by "the rolling process", but it sounds as though you might have exposure bracketing turned on.

[Peter]

Do you have the camera in M mode?

[Elieabihatem]

Yes M mode

[Peter]

You don't use af when video recording? Do you see that the aperture (what you call iris) is moving?

[Elieabihatem]

Im not using AF
And the aperture is not moving
Evrything is normal nothing is changing while rolling exept the exposure with no aperture changes

[Peter]

And would you like to upload a sample?

[Elieabihatem]

I dont have the footage now once i have it i will try to upload something

[Peter]

And you can also check if you will get the same in live view. With my 6D and an adapter for m42 mount my screen goes from dark to bright in live view.

[Elieabihatem]

Ok but u dont know what is the problem? I think in live view i have the same issues