Adding overscan region awareness to centering functions


I’ve recently enabled the overscan region on my STF-8300M to calibrate bias drift related to ambient temperature. I’ve found that this causes unexpected behavior as relates to image centering, and have had to disable this camera feature as a result.

In short, it’d be great to see the addition of settings for a “centering subframe” in the Plate Solving setup tab (or wherever it’d be most appropriate). This setting would cause a download of a subframe for centering purposes (much like what is already possible with manual focus subframes) that, if defined correctly by the user, would exclude the overscan regions and result in expected centering within the active sensor area.

This feature might also make sense for auto-focus frames; I don’t currently use a motorized focuser so am unfamiliar with existing SGP capabilities here.

As it stands currently without this support in SGP, overscan regions cause incorrect centering based on the active sensor area. The target center is offset in the active area by an amount equal to the size of the overscan regions. To make matters worse, after a meridian flip on the same target, the offset error is in the other direction relative to the target, resulting in a further crop of the active area when combined with previous frames.

I don’t think any changes would be necessary to the Framing & Mosaic Wizard in this regard. The camera resolution setup here could simply be defined by the user as the active sensor area rather than the entire resolution including overscan regions, effectively matching the “centering subframe” defined by the suggested new feature.

Let me know if I can elaborate further. I’d really love to see this feature so that I can utilize the overscan regions.