Meade Series 4000 f/6.3 Focal Reducer/Field Flattener (4-element/41mm dia.) for CCD, Photographic, & Visual Applications.

Series 4000 f/6.3 Focal Reducer/Field Flattener: An important advancement in high-resolution focal reduction systems, the Meade 4-element, multi-coated f/6.3 Focal Reducer threads on to the rear cell of any Meade LX-Series mirror Focal lens telescope or to other Schmidt-Cassegrain telescope brands (followed by the Off-Axis Guider, shown, or T-Adapter) and reduces the telescope's focal ratio by a factor of 0.63: e.g., f/10 telescopes are converted to f/6.3.

Simultaneously, the 41mm-diameter lens system helps to flatten the field, significantly improving edge-of-field corrections. The f/6.3 Focal Reducer enables a reduction of photographic exposure times by about 50%, while producing an actual field diameter of 1.5" at the film plane.