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Orion Optics OMC140


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Ian,

Out of interest what is the "weapon of choice" for double star afictionados? I'd guess a long fr Mak/Cass would be pretty high up the list?

Gaz

Gaz

The generally accepted 'best' type of scope is a refractor due to the lack of central obstruction. For tight doubles any CO will take the light from the primary and add it into the defraction aorund the star this will make seeing a companion that much more difficult. Also the difracrion spikes from the supports can cover a faint companion.

But large refractors are expensive and also to get a decent focal length and hence magnification they have to be very long!! The ideal length for a refractor for double stars is beteen F20-F40.

Because Newtonians are much cheaper for the money you can get a scope with decent aperture that allows you to see much fainter stars and if stars are of similar magnitude they are usually easily resolvable down to 1.5" (seeing dependant)

So in simple terms

Bright tight doubles - Refractor

Wider faint Doubels - Newt

and the OMC is a good compromise between the 2.

Here is a great web site on doubles. This link is the joke page.

http://www.carbonar.es/s33/33.html

Cheers

Ian

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