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Old 06-06-2014, 01:23 AM
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SamD (Sam)
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M42 Lenses plus Atik 314L+

I've bought a few Carl Zeiss and Asahi Pentax M42 lenses on Ebay in order to try some low f-ratio wide field Ha imaging with my Atik 314L+. I've already got a M42 to T2 adapter, got a place to slot a 1.25'' filter into, and got the back focus spacing worked out, but am wondering what options there are to physically attach the camera + lens to a mount (like EQ6 etc).

Problem is, beautiful as the red 314L+ is, there's no 1/4'' screw mount on the bottom like you have on DSLRs allowing piggyback mounting. I'm tempted to try a tripod collar mount ring of approximately the right size to go round the M42 lens. I thought about trying a normal tube ring around the circular Atik too.

Anyone tried this kind of set up before, or have experience of similar M42 lens set ups ?

I know there are Geoptik adaptors for Canon/Nikon lenses, but don't think there's one for M42 lenses. In any case, the Geoptik adaptors are quite expensive, compared to having a go with a budget tripod collar for under $10.
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Old 06-06-2014, 05:35 AM
gbeal
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Post a picture Sam, it can't be too difficult, might take a bit of #8 wire though.
My first Google gave this page full of images, but in it there are quite a few with camera lenses mounted, admittedly with the Geoptik style. I'd say from looking at the pictures you could get a collar made to go round the black round section on the camera front. Maybe.
Gary
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Old 16-07-2014, 01:27 PM
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SamD (Sam)
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Yes, without too much of a fight, managed to get everything snugly together for my M42 lenses:

Basically, I've filled the M42 44mm back focus with:
7mm: M42 x 1.0mm female to T2 male adaptor ("Russian" adapter)
21mm: Manual filter wheel
16mm: Atik 314L+ with standard nosepiece to CCD

The camera+lens can then be attached to a dovetail using a cheap ebay/Amazon tripod collar mount ring. I used a "Tripod Collar Mount Ring for Canon EF 70-200mm" which has a diameter about 1-2mm more than the diameter of suitable mount points on the M42 lenses. An extra turn or two of felt tape on the inside of the mount ring and on the narrower lenses gives a really secure coupling. (It's all for wide field stuff anyway so any small flexure is unlikely to be a problem).

The three M42 lenses I've tried so far have had a convenient area between the focussing ring and aperture ring to attach the collar mount ring too, and the whole camera+lens is reasonably well balanced. Manual focussing on the lens barrel is fine by hand, I just use the Artemis Capture software loop mode to get the smallest stars possible.

The idea is that you need shorter focal length lenses to squeeze the wider targets onto the "smallish", but "relatively cheapish" 314L+ chip. You get about 2.5 deg FOV at 200mm, or 3.7 deg at 135mm, and benefit from the fast f/3.5 or so.

First go in the dark was a couple of hours total of Ha/O/S at f/4 and 200mm on Eta Carinae Neb (still learning on narrowband colours!).
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