Cassegrains optimized for CCD

500mm f/9 Cassegrain with secondary focusing

Although we still produce the Hypergraph we have also taken into account the need for smaller fields and more focal options and think that the following telescope is a good allround telescope for the latest high performance CCD like the STL11K and other Large Format Cameras.

The main difference to the Hypergraph is that it can be used without corrector and allows the usage of an optional Reducer. Like the Hypergraph, the Cassegrain can be ordered with f/3 prime focus option.

We also offer an optional 2 lens field flattener and coma corrector for this telescope.

Optical performance that is always taking you to the seeing limit

the following spot diagrams show you clearly, why a Cassegrain with optimized correctors / reducers is superiour to most other telescopes, including the Ritchey Chretien telescopes.

There is a lot of myth about the performance of RC's, but the below spot diagrams show clearly, that a f/6 RC does not have a sufficient performance to cover a D=40mm field without a aditional corrector. Some RC manufacturers show spot diagrams for curved fields for their RC but unless you have a curved CCD you should better look at the true spot diagrams that should be calculated for flat field.

We CAN also offer RC telescopes witthout problems and we already made a lot, the price is appr. 15% higher then, but as you can see there is NO advantage thats justifies any higher price..

The spot diagrams show a field of 20mm Radius = 40mm diameter which roughly equals the field of the STL11K from SBIG.



these are the spot diagrams for our 4-lens 0.66x Reducer that we offer as an accessory

these are the spot diagrams for our 2-lens corrector that we offer as an accessory. This corrector does not change the focal length. Full usable field is 80mm diameter.

Prime focus option


If you  like fast speed and huge fields, the prime focus option might be interesting for you. The prime focus is permanently installed in front of the secondary mirror and by removing the secondary in its holder you allow the light path to reach the prime focus.
Switching between the 2 focal confogurations takes only 1 minute.


The spot diagram shows a field diameter of 64mm, so you are ready even for very large CCD's with this telescope. Please note, that the box size is now 25 micron so the spots are 4x enlarged here compared to the above spot diagrams.





We now offer as standard 400mm f/9, 500mm f/9 and 600mm f/9 systems. Please ask for prices.

If you want to see some sample images, please check out this:

check the "new" section.