Why no mirror telephotos for DSLR Canon?

Started Jan 25, 2010 | Discussions thread
Bill MacBeth
Senior MemberPosts: 1,631
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Re: I have a $700 1900mm f15
In reply to Lee Jay, Jan 29, 2010

ljfinger wrote:

Bill MacBeth wrote:

I sill have the telescope and need to know -- can a 5DM2 operate without a lens, to use eyepiece projection?

Yes, but eyepiece projection (a.k.a afocal) requires a lens on the camera. Otherwise, it's called "prime focus".

Lee Jay,
I guess your answer is yes, a 5DM2 will operate without a lens attached.

Here's what I mean by 'eyepiece projection'. I've used the technique many times on my on reflector, and on a larger refractor at a university. An eyepiece (normally used for visual observation) is moved away from the visual focal location, so that it profects a focused image about four inches outside itself. The film plane or sensor plane of the camera is placed at that location. No lens is used on the camera.

Prime focus (no eyepiece) projects an image too small for lunar and planetary photography, which is my intended use.

Regards, Bill

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