ASA Cassegrain- and RC-Systems

(design by Philipp Keller).

Cassegrain and RC telescopes are used by professional observatories, research institutions and universities. The most famous telescope in the world, the hubble space telescope - uses the Ritchey–Chrétien (RC) design. The telescopes which ASA has on offer - a design by Astrooptik Philipp Keller - have since years been considered the reference class in the professional and semi-professional area. ASA is pleased to announce its cooperation with Dipl. Phys. Keller, to build and market these telescopes systems.

The telescopes are made in open truss construction style with CFK-tubes and precision optics soley from Lomo Optics. ASA has on offer the optical sets or the complete telescope system which can be set up in a parallactic or alt az design.

In combination with the reducer correctors and field flateners designed by Philipp Keller, these intruments can also be used for large CCD sensors with diameters of 150mm and more and still display pin point stars all the way to the corners.

Spotdiagram

Aperature sizes are commonly available in 400, 500 and 600mm (16, 20 and 24inches - Cassegrain f9, RC f8). Offers for diameters of all other size up to one meter or beyond can be made upon request.

Pricelist

Best configuration possible: LOMO Optics inside!

LOMO Optics has established itself as a very reliable manufacturer of precision optics. Lomo also delivers optics for professional telescopes up to 2m in diameter. Lomo's mirrors are of the highest grade in the industry: If your aim is perfect imaging quality and you do not want to spend the few clear nights with inferior optics, then Lomo is the call. In order for the optics to provide optimal corrections also during cool of periods, we only offer our optical sets in either Astro Sitall or Zerodur ceramics. Prices for raw materials (blanks) change depending on availability. Prices will hence need to be calculated on request and will vary depending on size, material used (Sital or Zerodur) and availability.

LOMO offers perfect quality parabolic mirrors, flat optics as well as Cassegrain- and RC-Systems. Contrary to other optics vendors we deliver every optical set with test certificate and Interferogramm. For standard optical sets, we also offer a no-questions-asked return policy of up to 6 months.

Cassegrain- and Ritchey-Chretien-Systems

• System-wave front accuracy minimum L/8 Peak to Valley at 632 nm in focus
• System-wave front accuracy minimum L/35 RMS at 632 nm in focus
• Surface Quality 80/50 scratch/dig
• Coating Aluminium and Quarz, other coatings upon request

Cassegrain and Ritchey-Chretien-Systems compared

Optical performance that is always taking you to the seeing limit

The following spot diagrams show you clearly why a Cassegrain telescope with optimized correctors/reducers is superior to most other telescopes, including the Ritchey Chretien telescopes. There is a lot of myth about the performance of RC's, but the spot diagrams show clearly, that an f6 RC does not have performance sufficient enough to cover a D=40mm field unless an additional corrector is used. 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 need to be calculated for flat field.

A corrected Cassegrain System will always be superior to an uncorrected RC. The great benefit of the RC is that with very large CCD sensors the imaging field can be corrected in a better way. The spotdiagrams above will show a 20 mm Radius = 40 mm diameter which corresponds to a large format sensor.

PERFECT IMAGING PERFORMANCE

ASA Cassegrain- and RC-Systems

Best configuration possible: LOMO Optics inside!

Cassegrain- and Ritchey-Chretien-Systems

Cassegrain and Ritchey-Chretien-Systems compared

See the following links: