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.
