Black bars when underexposing the A7S??

rawfa

rawfa

Veteran
Guys, I just got an A7S and while doing some test I've realized that when I underexpose while filming I get some strange horizontal black bars. This doesn't happen with stills, only video. I've tested with the Zeiss 55mm 1.8 and with a Sigma 28mm 1.8 with the LAEA4. Anyone knows what's going on? I've checked the sensor and it seems fine (if it was the sensor then this should happen during stills too). I've also ran the in camera "auto sensor clean" (or whatever it's called)


Here is a test to show you guys what I'm talking about (I've just uploaded it so it may take like 15 minutes to become available on vimeo):

 
Looks exactly like banding due to the lighting. What kind of lights were in the room (fluorescent?) and what shutter speeds were you shooting at?
 
I've tested lowering the shutter speed to 50 and closing down the aperture and the bars went away. I'm going to test in daylight tomorrow...if it doesn't happen then it's the fluorescent lights.
 
Yup that's definitely just lighting flicker not matching shutter speed. It won't happen with non-flickering light sources or in daylight, and you can avoid it by matching your shutter to the light source flicker frequency.
 
It's your light source.

Fix, Point the camera at a blank white-ish wall, close down iris until you can see the bars clearly.

Then change the shutter speed in finest increments until you find one that makes the flickr go away.

Tthat's of course shooting under the same light you're using here.
 
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