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Old 29-12-2008, 06:29 PM
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Canon FD lens conversion

Some time ago I promised to describe my way of converting Canon FD lens to EOS mount..
Here it is:
The lens I converted was Canon 50mm F1.4 S.S.C.
First, I removed everything that has anything to do with FD mount. This was done by removing 3 screws (they can be reached by rotating the locking bring, between the bayonet cut-outs).
For adaptor, I used one of M42-EOS adaptors (from ebay, ~$10.00) and machined it like shown on image, to be able to reach the focus of my 400D... the depth of cut was 1mm (still 1m left on adaptor, more than enough). Since this is still ~0.7mm out of focus, the focus stop had to be adjusted as well. To reach it, I had to remove (unscrew) the plastic ring with letters from the front of the lens, using a rubber tool that made good contact with the ring and yet no contact at all with the glass of the lens. Then there are two other rings to remove, before the focus stop was available. The dismantling procedure is clearly illustrated on the pictures.
The focus stop is a small curved plate, 15mm long, tightened to focuser with 3 small screws. There are a number of redundant threaded holes on each side (we need those that are to the right), so it is easy to move this stop significantly without a need of any machining.
(I moved it ~12mm, to the next set of threaded holes).
To have a control (manual, of course) over aperture, I cut a piece of brass shim, and adjusted it such that the iris is fully opened when f-ring is set to 1.4.
And this is it.. I also machined a spacer (aluminium) to cover a gap between the lens and adaptor.
Now I am looking forward to do star tests :-)
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  #2  
Old 30-12-2008, 08:58 PM
Ian Robinson
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Or you could have bought one of these http://cgi.ebay.com/Converter-Adapte...3A1%7C294%3A50
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Old 30-12-2008, 09:02 PM
Ian Robinson
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I bought something similar for my Minolta MD lenses that coverts them to Canon EF , with convertor lens that allows focus at infinity ....
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Old 30-12-2008, 09:14 PM
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Ian, I was aware of conversion lenses for FD->EOS... but problem is, they add their own distortions. I strongly believe this is the better (and cheaper, at least for me) way. To reach infinity is not the problem here, I can even adjust it such that I never have to check focus for stars again (of course this will be for my camera only).
And the modification is not irreversible - however I can not think of any good reason to go back :-)
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Old 01-01-2009, 07:07 AM
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Canon 50mm f1.4 star test

The results of star test: the operation was highly successful, for under $100 I have excellent lens for my 400D.. have a look.. star images at f4 are pin-point sharp even in corners :-)
Images below are 200% crops from one raw frame around Canopus, taken last night and displayed with Digital Photo Professional editor.
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Last edited by bojan; 01-01-2009 at 09:49 AM.
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