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Old 11-12-2019, 10:24 AM
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The_bluester (Paul)
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Join Date: Feb 2011
Location: Kilmore, Australia
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For my ASI294, ZWO recommend not using bias frames. By my understanding it is related to the issues getting really effective flats for that camera. Any exposure below about 4 seconds is timed on chip by the SoC (System on a Chip) componentry of the IMX294 sensor itself, beyond that the ZWO circuitry takes over. That means the noise profile is different either side of the threshold so flats need to be 4 seconds + and bias frames would have a different profile.

That 4 seconds is an estimate I have seen, I have not found the exact figure unfortunately or I would use that. It means that flats need a very dim light source.
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