The
As far as being bright in the center this is common , use the exposure to knock that down , the darker areas closer to the edges will be easy to lighten back up in the processing .
There are many different shots we want to take , full disk ,proms , close up surface ect . Shooting a prom on the limb will take different tuning and camera settings than doing a close up of an AR .
I had Quark for about 5 years and will say that it produced a very even field for the camera and I did get some decent images with it but I found that my other options worked better for me . Having to shoot at
Mike