recently I acquired a sony ar7ii and have done about 2k photos with it. works amazingly, but occasionally i see these black bands.
The horizontal light and dark bands looks like a flickering issue, which is common with many artificial light sources. Some cameras have an anti-flickering setting. If such a setting is not available, you can try dropping the shutter speed to something like 1/40. If the problem goes away, you can gradually increase the shutter speed until just before banding reappears.
The problem is often associated with electronic rolling shutter. Unfortunately, the solution would be to adjust the readout time, which is out of your control.
Here is another effect associated with electronic rolling shutters:
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The banding seems similar to that from "rolling shutter", where parts of the image sensor are scanned sequentially during the flickering of fluorescent and LED lighting.
A few ways to avoid, or at least reduce, the problem:
- Use fill light from a source that doesn't flicker, such as daylight or incandescent lamps.
- Use a flash, either direct or bounced.
- Adjust the shutter speed to get a full cycle of AC power, which is 50 Hz in many countries, but 60 Hz in North America. I.E., Use 1/25 or 1/50 second most places, 1/30 or 1/60 second in N. A.
Experiment taking photos with your camera of a plain white surface lit by fluorescent or LED lamps, using different shutter speeds, to confirm if that is the issue and to see how best to fix it. N.B. Some LED lamps are more prone to flicker than others. Also, some fluorescent tube phosphors have longer persistence than others, so you might observe slightly colored bands.
This may be similar to another question about banding, though.