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12.1mm T Thread spacing...

AndyUK

By AndyUK
in Discussions - Scopes / Whole setups

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AndyUK

AndyUK

Posted
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I've never had to deal with spacing before... but here I am considering buying a Geoptik lens adapter for use with my 314L+ and I really can't wrap my head around what I need to buy with it - Here's the maths of what I've discovered:

The Adapter itself is 18.8mm (excluding the 4mm long T2 thread on the camera end). On the Atik 314L+ there's a distance of exactly 13.1mm from the black front end of the nosepiece to the focal plane of the CCD sensor - Adding these two together I get 31.9mm.

The flange focal distance of a Canon EF system is always 44.0mm, so I reckon I need a spacer of 12.1mm... but I've looked up LOADS of spacers and can't see how I can make up this distance - Geoptik make a variable spacer which covers 7.4-9.5mm, so if I could find a 3 or 4mm spacer to add to it that would do it... But I can't find one. So I've been trying to see if anyone makes a 12mm spacer... :(

Am I missing something, or just being stupid? I can't believe that I'm the only person to have ever wanted to put an Atik 314L+ onto a Canon lens...

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AndyUK

AndyUK

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Excellent...! Whilst on that site, I've now found a Baader variable locking T-2 Extension 12-16mm that might do the job in one piece (although I note that they're saying it's out of stock :(). Thanks very much for the pointer...!

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Stephen

Stephen

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Excellent...! Whilst on that site, I've now found a Baader variable locking T-2 Extension 12-16mm that might do the job in one piece (although I note that they're saying it's out of stock :)). Thanks very much for the pointer...!

I've had some good dealings with Zoltan recently. Drop him an email. He will tell you if he's got one lying around, and if not he will order it and tell you how long it will take :(

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  • 5 months later...
michael8554

michael8554

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AndyUK have you tried focusing your Canon lens with the spacing you have already?

So long as the Canon flange to CCD is 44mm OR LESS you should be able to focus.

Well maybe not with 12mm too short, but adding 10mm will definitely work.

Unless you really can't live with the infinity mark on your lens focuser not being exactly opposite the datum line.

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AndyUK

AndyUK

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Hi Michael - I think I got this sorted with one of these - Baader Adapter T2 Verlängerung 12-16mm variabel # 33, although to date, I've only tried the Geoptik once (:)), and that wasn't really in anger, only as a test...

However, it looks as though I'm going to have another spacing problem to battle with shortly and I was intending trying my existing adjustable spacer with that first, to see if I needed to buy another one... but if it works, then I'll only need to buy a 10mm tube for the Geoptik and save myself a bit of cash :D - Thanks!

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  • 5 years later...
usingen1

usingen1

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They must have made the spacer too short on purpose so that you need to buy more spacers because we all know that it needs 12.1 mm and the 9.5 max is just not enough this is what sucks when all the manufacturers make junk and you need to spend more money just to get the things to work instead of working out of the box.  I am not aware of ANY Canon lens that will focus with less than 44 mm total BF. :hmh: it just totally sucks

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