SHARPSTAR 2.5" FIELD FLATTENER 1.0x GSO the backfocus of some telescopes

the backfocus of some telescopes is so short that it is not possible to use a standard  camera adapter which have a thickness of roughly 10 mm

tracking or pointing objects

alloy steel

The optical design includes a lens and a two element flattener group situated before the focal plane

SHARPSTAR 2.5" FIELD FLATTENER 1.0x GSO the backfocus of some telescopesThe SharpStar 2. 5" field flattener is one of the best and most universal correctors for apochromatic refractors. It delivers a fully illuminated circle for the full frame (24mm x 36mm) and a corrected image circle up to 55mm. Differently from many other flatteners, it does not reduce the native focal length of your telescope. In other words, its magnification is x1. 0. This allows the full use of the power of the telescope. The flattener is suitable