Image centering with overscan enabled images


I use overscan enabled images on my QSI583. This adds 279 pixel columns to the right. When doing plate solving and image centering, I think SGP may not take this into account. Could you please confirm?

Also, using the crosshairs for image center is definitely out by half the overscan width. See attached image.

Wondering if there could be a feature in the camera properties to put in overscan width so it’s allowed for in plate solving and image display on screen? Or at least the crosshairs could be offset to assist using the right click, center image here feature?


Any thoughts or ideas?


I would say disable the over scan but I’m assuming you have it turned on
for some reason?

Jared Wellman
Co-Owner and Developer
Main Sequence Software


Thanks mate. I guess that’s the easy solution. :smile:
Reason I enabled it was a mate had been testing and getting a few percent better S/N. I wanted to try it out for myself.
I’ll probably just disable it for now.
Wasn’t sure if it was a quick fix for you guys, maybe treated as a feature request or enhancement to be made in the future?


I don’t think we would be able to do anything to address this. I’m not
100% sure, but I don’t think we would have access to overscan data for most
cameras so we wouldn’t know how to adjust image center.


Wasn’t expecting it to be automatically detected. Was just thinking in the camera settings you could have a checkbox to “enable” overscan, and the user could simply add the number of columns manually. It should be reasonable to assume that someone using overscan should know how many columns etc. Then just use this number in the image centering calculations if overscan is checked, else number of columns is zero.


There’s no overscan property in the ASCOM camera specification.

A generic fix in SGP would be a centre offset parameter that specified the offset of the centre (in pixels in X and Y). This could have other uses, such as adjusting the framing of an object.



First time posting, so I hope it’s right to continue this older discussion rather than create a new one as there isn’t a resolution identified as of yet.

It’d be an excellent extension to the framing & mosaic wizard and SGP centering capabilities to introduce a user-defined overscan region offset that would provide expected framing and proper centering on each side of the meridian with this feature enabled. Pinpoint centering with overscan enabled is practically impossible otherwise. My frames benefit from overscan calibration, but until an associated feature is available in SGP, I’ll need to reluctantly continue without overscanning.

The overscan regions on my STF-8300M add 200 rows (right side) and 200 columns (bottom side) to the frame. The first issue I found is that since the framing and mosaic wizard is unaware of this non-imaging region, the “center” isn’t really the center. Currently, the only way to account for it here is to eyeball it. The second and more painful issue comes at a meridian flip: Since the overscan regions have now flipped orientation, the imaging center offset has also flipped orientation, and centering results in an imaging region shifted the twice the size of the overscan regions.

I’ll reiterate what was stated earlier in the discussion: I don’t think the regions need to be automatically detected. Much like the camera data is entered manually, I think it’s perfectly appropriate that the overscan regions could also be manually identified by the user and saved with the profile.

Hope this is helpful feedback. I’d love to see this feature.


Please start a new topic and place it in the Feature Requests category. Features outside this category (like this one) will not be considered for implementation (it is too time consuming to try and figure out which posts are requests).



Makes sense and will do. Thanks Ken.