The primary optical aberration of fast Newtonian telescopes is coma, which causes stars to become increasingly elongated rather than remaining pinpoint-sharp toward the edge of the field of view. In f/5 systems or those with even faster focal ratios, this can already be visually distracting, but coma becomes a truly serious issue in astrophotography. The solution is a coma corrector inserted into the focuser, and among these, the TeleVue ParaCorr Type-2 stands far above its competitors.
The Paracorr effectively eliminates coma in Newtonian telescopes with focal ratios down to f/3. This provides perfectly pinpoint stars even at the edge of the field of view, for both visual observing and astrophotography. A major advantage of the TeleVue coma corrector is that it introduces no harmful aberrations, such as chromatic or spherical aberration, and light transmission is not noticeably reduced. It increases the telescope’s effective focal length by only approximately 15% and can be used with both 1.25" and 2" eyepieces.
For astrophotography, the corrector can be used with the eyepiece extension removed. It provides perfect illumination even for APS-C-sized image sensors (e.g. Canon EOS cameras) in telescopes with focal ratios as fast as f/3. Its ideal sensor distance is approximately 55 mm. Image sharpness remains perfect across the entire field of view, free from spherical and chromatic aberration, with no distorted stars at the edge of the field either. The corrector can be adapted to Canon EOS cameras or other digital cameras using the Paracorr-T2 adapter.