The Deltagraph is made for CCD and medium format (6x7) by Philipp Keller Germany. It has a 30cm aspherical mirror (by Lomo/Russia!) and a 3-lens-corrector designed to fill a 6x7 field with no vignetting (star diameter in corners is less than 0.025mm). The corrector is especially designed for wavelengths from 400nm to 700nm. The carbon construction tube guarantees focus stability.
Weigths 16kg with tube rings and adapter plate. Electrical focusing unit and film holder (all included). There is no diagonal mirror, the film holder or CCD is on top of the corrector. Easy focussing via ccd/video/foucault (not included).
There are several fantastic results with Deltagraphs in the web. There was a 10" version before, but Philipp stopped construction because the (ccd not centered) sbig-cameras caused vigentting - not so with the 12"! This one was finished in March 2003. According to healthy problems (of my friend who asked my to place the ad in Astromart) it never had first ligth.
Please ask me for more details. I can also arrange contact to owner (who's english is even worse than mine) and P.Keller who can approve the originaltity of this Deltagraph.
Waiting time for a new one is typically one year. Asking 6.200 Euros incl. immediate shipping (UPS,Insurance).
Picture shows the Deltagraph beside a tripod an a Vixen GP-DX mount
p.s. this is not a Hypergraph which is 3 times the price of a Deltagraph. The Hypergraph has a truss design and works with a Deltagraph like prime focus mode and a corrected (kind of) f/9 Cassegrain mode.