Massimo Riccardi , a well-known optics designer from Italy, has calculated a 3-line 0.75x reducer / flattener for APM-LZOS apochromatic telescopes, which is also suitable for many apos from other manufacturers. The reducer reduces the focal length by a quarter and corrects the image field. Turn your telescope into a fast astrograph!
Installation: The connection to the telescope and the camera is done with a M63 x 1 thread. For exact adjustment when tilting the reducer / flattener, you can also use an adjustment flange.
Backfocus: The backfocus is adjusted according to the telescope used. The exact value for your device can be found in the PDF document. The total optical length of the Reducer plus Backfocus plus focus is between 160 mm and 180 mm.
In the case of eyepieces with a free aperture of 68 mm, the reducer can also be sunk with an adapter in the eyepiece ejector.
The correction is designed to the full format and also perfect for the widely used Kodak KAF 8300 chip.