61EDPHⅢ full frame flattener

The flattener: One end of the thread is M68 × 1, connected to the focuser; the other end of the thread is M48 × 0.75 and has a built-in 2" filter thread. The back focus is 55mm. If it needs to be extended, the adapter can be screwed down to reveal the M54 × 0.75 male thread, and the back focus becomes 81.5mm. The flattener adopts a triplet air-spaced structure, the peripheral light reduction control is excellent, can effectively improve the curvature of the field, improve the corner image quality, and reduce aberrations so that users can take clearer astronomical photos.