- Edited
Tech@ZWO The default value is 3.
The ASIAIR default for this camera is total garbage.
This is a subframe captured on ASIAIR from a few hours ago with the ASI585MC cooled to -10ºC. Gain is set to +25.2 dB, and exposure duration is 20 seconds (this is where the read noise and ther dark current noise balances out -- the ASI585 is a very noisy camera) with the IDAS NBZ-II filter on a Takahashi FSQ-85 at f/4.5.
In case you do not see what is wrong, take a look at the Min ADU.
For those of you who are stuck with using the ASIAIR, do not buy this camera, since the ZWO default offset is too small, and ZWO does not allow you to change the ADC offset in ASIAIR.
For those of you who are using some other image capture software, increase the default offset so that the MIn ADU is solidly off from 0 (at least 99.7% -- 3 sigma for Gaussian distribution -- of the time). A Min ADU of 0 means that a stack of images will not reduce the noise variance by half each time you double the number of subframes. The noise will remain high even if you stack more subframes.
Chen