{"id":93329,"date":"2026-01-10T14:01:10","date_gmt":"2026-01-10T13:01:10","guid":{"rendered":"https:\/\/www.telescoop.nl\/?post_type=product&p=93329"},"modified":"2026-09-04T14:05:00","modified_gmt":"2026-09-04T12:05:00","slug":"omegon-primary-mirror-304mm-f8-ritchey-chretien-mirror-set","status":"publish","type":"product","link":"https:\/\/www.telescoop.nl\/en\/omegon-hoofdspiegel-304mm-f8-ritchey-chretien-spiegelset\/","title":{"rendered":"Omegon Primary Mirror 304 mm f\/8 Ritchey-Chretien Mirror Set"},"content":{"rendered":"

Omegon Main mirror 304 mm f\/8 Ritchey-Chretien mirror set: main mirror and captive mirror for DIY installation<\/strong><\/h2>\n\n\n\n

A Ritchey-Chr\u00e9tien uses two hyperbolic mirrors instead of the parabolic primary mirror of a Newtonian or the spherical mirrors of a Schmidt-Cassegrain. This combination completely eliminates coma, so that stars remain round right to the corners of the field of view. That is why this is the design of virtually every professional observatory.<\/p>\n\n\n\n

This set includes the optics, not the tube. It is intended for builders who are building a truss structure themselves or who want to retrofit an existing tube with new optics. With a 12-inch opening, you capture significantly more light than with the 10-inch version, which translates into shorter exposure times.<\/p>\n\n\n\n

\"Omegon<\/figure>
\"Omegon<\/figure>
\"Omegon<\/figure><\/figure>\n\n\n\n
\n
\n
\"Omegon<\/figure>\n<\/div>\n\n\n\n
\n

Quartz glass for a stable focus<\/h4>\n\n\n\n

Both mirrors are made of fused silica, also known as quartz glass. That material hardly expands with temperature changes.<\/p>\n\n\n\n

That is exactly what long exposures are all about. A mirror made of ordinary glass slightly changes shape during the night as the temperature drops, and then the focus drifts. Quartz holds its shape.<\/p>\n<\/div>\n<\/div>\n\n\n\n

\n
\n
\"Omegon<\/figure>\n<\/div>\n\n\n\n
\n

Coating with 94 percent reflection<\/h4>\n\n\n\n

Both mirrors have an aluminum layer with a protective layer of silicon dioxide over it. The reflection is 94 percent per surface.<\/p>\n\n\n\n

In a two-mirror system, that counts double: the light bounces twice before it reaches the camera. As a result, every percentage point of increased reflection per mirror has a stronger impact than in a single-mirror system.<\/p>\n<\/div>\n<\/div>\n\n\n\n

\n
\n
\"Omegon<\/figure>\n<\/div>\n\n\n\n
\n

Focal length and scale<\/h4>\n\n\n\n

At f\/8, the focal length is 2432 mm. This provides a large field of view, suitable for small deep-sky objects such as globular clusters and compact star clusters.<\/p>\n\n\n\n

Please note that a long focal length places high demands on tracking. Accurate mounting and autoguiding are not a luxury, but a prerequisite.<\/p>\n<\/div>\n<\/div>\n\n\n\n

Included<\/h3>\n\n\n\n