Problem Shooting Projector

[Van Royko]

Hi

I have been called to solve a problem while shooting a projector image with a RED. The projector is a Cinealta SRX-R105.

This is the description of the technical problem I received (I havnt seen it myself yet):
We have a strobing effect only perceptible when looking at the monitor.
There were no strobing effect when projecting colors from the projector.
It is not a frame rate problem since the strobing occured even when projecting a still frame, etc.

I personally think it might be a synch issue like what one would get with HMI lights-

any other guesses?

Thanks

[Clint Johnson]

My guess? Since projectors can't just project a still image, it is a frame rate versus refresh rate issue. The LCD in the projector is refreshed so many times per second and it seems that the Red's frame rate is set to a multiple or divisor of that rate. I don't have the specifications for that projector on hand or know what the frame rate you are using but examples would be if the projector has a refresh rate of 60Hz and the Red is set to 120fps- or if the projector refreshes at 120Hz and the Red is set to 24fps... then they can sync up and produce a strobing effect.

[LEON]

"I personally think it might be a synch issue like what one would get with HMI lights"

YES and to solve this, try different shutter speeds, good day.

[Robert Berger]

when you shoot instead of the projector a lcd screen with the same material, do you have the same problem? can also be that your materiaal is based on a 2xthe same field and no producing single frames?

love to hear more information,

regards
Robert

[JanneJansson]

Make sure frame rates are same.
Try changing the shutter speed.
Try syncing the projector to the cam and vise vers using a BNC cable.
If all fails, mess arround with the settings in the projector.