“These images shows a typical 10" Schmidt cassegrain quality, not the best, but also not the worst. It has some minor spherical errors and around the central hole you see on one side two dimmer rings and on the other side these two inner rings that are a bit brighter, which comes from a zonal error. In general this is a telescope with acceptable good optics”
Markus Ludes (APM-Telescopes)
Note: ronchi-testing with 254 lines/inch or 100 lines/cm.