Omegon Primary Mirror 254 mm f/8 Ritchey-Chretien Mirror Set

Omegon Hoofdspiegel 254 mm f/8 Ritchey-Chretien Spiegelset: hoofdspiegel en vangspiegel voor zelfbouw

A Ritchey-Chrétien 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.

Deze set bevat de optiek, niet de buis. Hij is bedoeld voor bouwers die zelf een trussconstructie maken of een bestaande buis van nieuwe optiek willen voorzien. Deze maat van 10 inch is de instap in de reeks en de meest hanteerbare van de vier.

Quartz glass for a stable focus

Both mirrors are made of fused silica, also known as quartz glass. That material hardly expands with temperature changes.

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.

Coating with 94 percent reflection

Both mirrors have an aluminum layer with a protective layer of silicon dioxide over it. The reflection is 94 percent per surface.

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.

Focal length and scale

Bij f/8 komt de brandpuntsafstand uit op 2000 mm. Dat levert een grote beeldschaal op, geschikt voor kleine deep-sky-objecten zoals bolhopen en compacte sterrenstelsels.

Please note that a long focal length places high demands on tracking. Accurate mounting and autoguiding are not a luxury, but a prerequisite.

Included

• Hyperbolische hoofdspiegel van 254 mm
• Matching secondary mirror
• Both with aluminum and silicon dioxide coating

Featured accessories

For aligning a Ritchey-Chrétien, a collimation eyepiece is the recommended tool: a laser does not suffice here because both mirrors are hyperbolic and the alignment is more sensitive.

For whom yes and for whom no

• ✓ Experienced builders assembling an RC truss structure
• ✓ Astrophotographers who want coma-free images right to the corners
• ✓ Anyone who wants to equip an existing tube with better optics
• ✗ Beginners: this is optics without tube, mount, or focuser
• ✗ For those who want to perceive visually: an RC is a photographic design
• ✗ Setups without autoguiding: the focal length is too long

Specifications

You can find more telescope parts for this merk on the Omegon merk Page.