Parabolic mirror cannot create perfect image in a larger distance from a field of view center without image distortion caused by so-called “coma” aberration (this aberration is inherent to all parabolic mirrors). So it is necessary to use coma-corrector optical device, which significantly reduces this aberration, when using CCD camera with large detector.

The lenses used in the TeleVue Paracorr PSB-1100 are significantly larger compared to the lenses used in e.g. in Paracorr PLA-1100 or other coma-correctors intended for T-thread mount, so it does not cause vignetting even on large “photographic full-frame” 24 × 36 mm CCD detectors. The adapter for TeleVue Paracorr PSB-1100 is attached to the camera body by the same way like other adapters for various telescope/lens standards—using four metric M3 screws. So replacing of the adapter is very easy and the only tool necessary is the Phillips screwdriver.

The Paracorr PSB-1100 adapter preserves the required distance between the thread front side and the CCD detector to achieve optimal correction of coma aberration of parabolic mirrors. Still the G3 camera body contains enough room for mechanical shutter and a filter wheel with 5 positions for filters up to 10 mm thick.