The Optec NGM (Next Generation MaxField) telecompressor increases the effective speed of the Meade and Celestron Schmidt-Cassegrain telescopes from f/10 to f/3.3. This 3 fold reduction in focal length allows for 9 times greater field area and 1/9 reduction in exposure time for extended surface objects such as bright nebulae. The system is optimized specifically for f/10 Schmidt-Cassegrain telescopes to allow for the correction of field curvature and spherical chromatism that afflicts these types of instruments. At f/3.3, the maximum corrected field has a diameter of 9 mm at the image plane which makes the unit suitable for CCD cameras with imaging chips of the same diagonal dimension or smaller.
The optical design of the NextGEN 0.33X was done with Zemax and optimized for four field points using wavelengths of 450, 550 and 650 nm. The goal was for the smallest blur diameters for the four field points. The system was modeled using the actual optical prescription for a SCT with the inherit aberrations of this telescope. The resulting lens curvatures of this designed were made without adjusting the radii to the optical lab's tool list. Custom tools were made for all surfaces.