I would like to be able to the annulus, which can be defined for full frame focusing, when I am using a sub frame.

This would work more or less the same as it currently works for the full frame where it selects the star but then uses a sub frame to perform the actual focus.

My justification is that I have found the star autoselect frequently chooses non stellar objects, such as globular clusters, and then the focus rioutine has a difficult time trying to arrive at the optimal focus position, sometimes failing completely. By forcing the routine to avoid the most congested areas in the image, which I can manually select, should improve the experience considerably.

Paul