Chronos > Software Dev

Horizontal banding

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tesla500:
Partially taping up the fan is an acceptable workaround. Even with the fan completely stopped or blocked up, the camera stays at a safe, albeit uncomfortable-to-hold, temperature.

I believe what is happening here is that the low temperature is causing an offset that's resulting in a black scene clipping to zero, which it shouldn't do. This would cause black cal to not completely remove the horizontal band, since it was all clipped to black when the lens cap was on. I'll look into this, it should be a simple software fix of adjusting the ADC offset slightly higher.

The sensor does have a temperature sensor, so it will be possible to automatically correct for the offset variations with changing temperature once we have time to implement the fix.

John Delonghi:

--- Quote from: JamesB on February 08, 2018, 07:56:10 PM ---I tried to replicate the problem but after black calibration, it went away every time on my unit. Glad I checked this post as I was wrestling with the same issue.  If you accidentally change the shutter even a little with the scroll bar it may come back.  I also found that if you do two black calibrations a few minutes apart the banding goes much lower.    :)

--- End quote ---

This is also good advice. Even at room temperature, when I turned on the camera just now the banding re-appears if I change the shutter. So it's obviously critical to do the black cal again if you change the shutter speed and immediately before recording again.

One thing I tried was to change the offset, as the banding always seems to be in the lower third of the frame. When I set the vertical offset to 0 the view on the LCD is still centred and the banding still appears in the same place. Is this what you would expect?

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