Quote:
Originally Posted by glend
ZWO publish graphs that are very useful for picking Gain and offset settings. Here us an example,
Just scroll down to the graphs.
https://astronomy-imaging-camera.com...asi1600mm-cool
You can see that Gain is marked at about 139 (ADU), and is usually referred to as Unity Gain in those cameras. We used to play around with different Offset figures (like 20), when these cameras first appeared, and I believe ASI cameras now come with a fixed Offset (others may comment further on this). I used to shoot alot at Gain 139, and Gain 76 (which seemed to be a good compromise setting where well depth is better, Dynamic Range slightly better, and noise was not significant enough to be an issue. Now I believe ZWO fix Offset in the driver, but again I could be wrong, as I sold my ASI1600 a couple of years ago.
A IIS member (Shiraz, aka Ray) actually published a series of charts for various ZWO cameras and he worked out an ideal ADU target, which i recall was around 600-800. I suggest you contact him as he was the expert on the figures for a range of ASI camera models. |
It is possible to change the offset on ZWO cameras with the ASCOM driver (at least with my 533 it is) and I am fairly sure the same is possible with the native ZWO driver, but I don't use that. The default 'unity gain' settings of 100 gain 70 offset on the 533 deliver a minimum ADU of around 2500(ish) whilst lowering offset to 20 brings the minimum ADU down to around 620. I have not yet established whether this makes any real world difference to imaging.