PlaneWave Instruments - Corrected Dall-Kirkham Telescopes

The CDK telescope is a brand new optical design invented by Dave Rowe.  The
goal of the design is to make an affordable astrographic telescope with a
large enough imaging plane to take advantage of the large format CCD
cameras of today.  Most telescope images degrade as you move off-axis from
either coma, off-axis astigmatism, or field curvature.  The CDK design
suffers from none of these problems.  The CDK is coma free, has no off-axis
astigmatism, and has a flat field.  The design is a simple and elegant
solution to the problems posed above.  The CDK consists of three
components:  an ellipsoidal primary mirror, a spherical secondary mirror
and a lens group.  All these components are optimized to work in concert in
order to create superb pinpoint stars across the entire 42mm image plane.