Last night I discovered that I wasn’t able to change the gain setting on the camera using the V4L2 API. No matter what setting I used all my captures turned out the same, using what I presume to be the default gain of setting of zero.
I know the gain settings can be changed under Windows, but I couldn’t see what I might be doing that was wrong and was on the point of abandoning the idea of using the camera when it occurred to me that perhaps the gain setting can only be altered after streaming from the camera has been started. This isn’t the case with exposure, which can be set before streaming starts. So as a last resort I re-coded my capture app to set the gain after enabling streaming and amazingly it all started working.
So now I just need to get some testing done under the stars. I’m a little concerned that using the “fish-eye” lens with such a large field of view I may not get enough light from a single star onto one pixel for it to give a clear image, but the only way to find out is to do some testing.