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Old 10-08-2017, 10:49 PM
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Shiraz (Ray)
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Shiraz is offline
Join Date: Apr 2010
Location: ardrossan south australia
Posts: 4,822
thanks Colin and Glen.
thanks for the concern Glen - am 70 - down this end of the bowling alley, everything is serious

FWIW, also found that dark scaling to account to correct for gain can work. Had a 10min master dark taken at gain 200 and used it to dark cal a sub taken at 10 min gain 100.

the gain 200 dark was scaled by 0.3, which is about the difference in gain from the ZWO website - the scaling function used is shown in the image, which shows the "glow" region from the bottom right of the Helix sub, before and after calibration. The data had offsets sufficient to ensure that there was no excursion below zero.

As with time scaling, manual dark scaling to account for gain cleaned up the warm pixels and the fixed pattern and worked well enough to be usable - again, not recommending it as a standard procedure, but pointing out that it can work OK if all else fails. Regards Ray

Last edited by Shiraz; 11-08-2017 at 06:24 AM.
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