Rafa Barberá replied to the topic 'Automatic Offset Calculation' in the forum. 3 years ago

Yes, offset varies from model to model, but also from camera specimen to camera. So two ASI533MC could have different offset. A lookup table could be valid only if we put there maximum values. It will be better to have a "sensor analysis tool" as sharpcap has. Also, you can perform this analysis by hand:

1. Put the cap on the camera / telescope.
2. Set the desired gain and enable cooling if your camera has the option.
3. Put offset to 0.
4. Take a 30s dark

You can see that the maximum histogram peak is to the left, touching the zero border. This will mean shadow clipping, so you need to increase the offset. Increment offset by 5 or 10 and repeat. Repeat until you can see a gap between the left histogram border and the beginning of the dark frame maximum peak. This will be the optimal offset for your camera at this gain (maximum range and no shadow clipping).

I've performed this analysis on my ASI533MC and a good offset for me is 30 at unit gain. The ASCOM driver for this camera has a backed in value of 70 that is safe from the point of view of manufacturing tolerances, but very high for my concrete sample :).

So if INDI ends having an offsets table defined, I hope that those values will be only recommendation and we can override them.

Regards

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