Horizontal Lines

[Christoffer Glans]

I experienced a weird thing looking at some test footage. There seem to be horizontal lines in the image, either darker or brighter than the background. However I can't seem to replicate it. We shot this with a back projection and the ISO somewhat cranked up to 1600/3200.
I'm at this time only able to see it on footage aimed at the background. I was trying to figure out if there was something with the shutter speed against the projector, but that shouldn't be an issue (50hz Europe with 225 angle shutter) and the lines are constant not moving as they do when having a sync issue.

Why do you think it looks like this? Are we talking sensor problems or things like that? I've yet to do a recal on the black shading though.

(Check the clouds above the girl; the darker horizontal lines)
Check

 

[Christoffer Glans]

No one?

 

[Robert Hart]

My computer databogs on the playback of your clip so I can't see the artifact well. There seems to be a soft indistinct shading drift in darker areas across the image from lower left to upper right, almost as if somebody was smoking near your rear projector and the smoke drifting between projector and screen. Is your reverse projection a motion image or a still image? If there are fixed bands in your image which I cannot see in my playback, it may be that there is slight variation in the brightness of your projector lamp which may be power-frequency related and an artifact of the sensor in your camera. Did you have any stray light from a LED or discharge source falling on the front of your rear projection screen and contaminating the rear projected image? Hopefully better observers than I can help you.

 

[Kemalettin Sert]

are you on beta? i have lots of problems with beta, do not use it..

 

[Christoffer Glans]

My computer databogs on the playback of your clip so I can't see the artifact well. There seems to be a soft indistinct shading drift in darker areas across the image from lower left to upper right, almost as if somebody was smoking near your rear projector and the smoke drifting between projector and screen. Is your reverse projection a motion image or a still image? If there are fixed bands in your image which I cannot see in my playback, it may be that there is slight variation in the brightness of your projector lamp which may be power-frequency related and an artifact of the sensor in your camera. Did you have any stray light from a LED or discharge source falling on the front of your rear projection screen and contaminating the rear projected image? Hopefully better observers than I can help you.

No, I'm talking about dark shade lines that are fixed to the camera, i.e it's the camera not something in the room or the projector. Check the clouds above her, that's where they are.

are you on beta? i have lots of problems with beta, do not use it..

Nope, it's not the Beta, it's the release built before that. But the thing is that I have trouble replicating it. I've tried the same settings, I've tried shooting against flat shade backgrounds etc. and I can't seem to get the same thing to happen. So I don't understand why this happened on that test shoot.