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12-19-2009, 08:47 PM   #1
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Canon FD to K-mount

The lens was listed as a Tokina 400mm f5.6 SD lens for Pentax. Today it arrived in superb condition with the original bag... in Canon FD Mount. For $20 shipped to the door it was not worth complaining/returning. A search of the net gave all the replies that the conversion/adapters can't be done, don't exist. Since its snowing and chilly, out came the tools and an old beat-up kmount from a long dead lens. I removed all the FD mount parts and found that matching up the kmount seemed to produce acceptable focus. A few ridges needed to be ground off with the dremel tool to even out the base for the k mount. After about an hours (sloppy) tinkering, the lens was ready to test. I had to forgo the ability to change the f stops so it is now a fixed 400mm f5.6 lens. Since it is dark out, further tests will be made on sunday. It does look like I have infinity focus. Heres a few pics of the breakdown/conversion.


Last edited by ivoire; 11-07-2010 at 10:09 PM.
12-19-2009, 08:50 PM   #2
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And some quick snaps with the lens on the k7

Last edited by ivoire; 11-07-2010 at 10:09 PM.
12-19-2009, 09:11 PM   #3
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I have a newer version in KA mount that's pretty nice. If you can't stop down, you'll have some CA.

I managed to make a C/FD mount Vivitar 55mm f2.8 macro into a sort-of functional K-mount. With a macro, I didn't worry about infinity focus. I ended up with focus to about 4 feet. I was able to get the aperture ring connected to the aperture, so it works like a manual aperture screw-mount lens. I have to guess a little about the exact aperture number, but if I move the ring in Av mode and shutter speed doubles, that's a stop, so no big deal.
12-20-2009, 12:00 AM   #4
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QuoteQuote:
Ivoire: The lens was listed as a Tokina 400mm f5.6 SD lens for Pentax. Today it arrived in superb condition with the original bag... in Canon FD Mount. For $20 shipped to the door it was not worth complaining/returning. A search of the net gave all the replies that the conversion/adapters can't be done, don't exist. Since its snowing and chilly, out came the tools and an old beat-up kmount from a long dead lens. I removed all the FD mount parts and found that matching up the kmount seemed to produce acceptable focus. A few ridges needed to be ground off with the dremel tool to even out the base for the k mount. After about an hours (sloppy) tinkering, the lens was ready to test. I had to forgo the ability to change the f stops so it is now a fixed 400mm f5.6 lens. Since it is dark out, further tests will be made on sunday. It does look like I have infinity focus. Heres a few pics of the breakdown/conversion.
Like you, by mistake I once got a Canon FD mount lens on Ebay. However, unlike you, I did not make good on the deal by working through the problem--congratulations! Perhaps this will inspire me to get my butt in gear and put my Vivitar (Komine) f 2.8 135mm through the transformation too. I owe you one.

12-20-2009, 12:13 AM   #5
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I converted a Vivitar Close Focus 2/28mm from FD to M42 (thread) with infinity focus and manual stop down.

It was tricky as I had to come up with a new mechanism to close the aperture down. I think normally (at least with this lens) turning the aperture ring moves something in the FD-mount (much more moving parts than in K-mount btw) from which a linkage closes the aperture when taking a shot.
12-20-2009, 02:08 AM   #6
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A friend of mine uses FD mount lenses reversed. He's still able to stop down, somehow.
While doing a Google search it looks like some people just use a wedge, allowing them to stop down. Made out of a Q-Tip somehow
12-20-2009, 10:07 AM   #7
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QuoteOriginally posted by ovim Quote
...It was tricky as I had to come up with a new mechanism to close the aperture down. I think normally (at least with this lens) turning the aperture ring moves something in the FD-mount (much more moving parts than in K-mount btw) from which a linkage closes the aperture when taking a shot.
Yeah, all the parts you want to remove to get the registration distance right are the parts you need for the aperture ring-to-aperture connection. I was hoping that on a third-party lens, there was some easier solution.
12-20-2009, 11:26 AM   #8
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QuoteOriginally posted by Just1MoreDave Quote
Yeah, all the parts you want to remove to get the registration distance right are the parts you need for the aperture ring-to-aperture connection. I was hoping that on a third-party lens, there was some easier solution.
That was the exact problem. There are 2 levers, one about an inch long and the other 1.5 inches, both attached to the parts that require removal to get proper registry. Being a hack and not a mechanic, I don't have the tools to fabricate parts. A 400mm f5.6 fixed for $20 and a bit of work is not bad. But I don't think I'll be buying any lens in the future without a pic of the mount. Lens salvaged and lesson learned.

12-20-2009, 08:01 PM   #9
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Wow nice! I wonder if I will be able to do similar conversion

I bought for cheap a used Canon Pellix with FL 55mm 1.2 lens attached to it. I intend to convert it to PK mount. Since I have no experience at all I'm not sure if I can really do it.. Also, I won't expect infinity focus, just being able to mount it to Pentax dslr and focus on medium range (like 5-10m) is good enough for me.

The Pellix camera itself seems working fine, mechanically, but the mirror is busted. Some part of mirror surface is almost peeled off. I can't seem to get anything in focus, always blur. But it doesn't matter since I'm interested more to the lens. It's such a pretty lens, which is why it's been a week and I still couldn't bring myself to break it open haha.
Anyway, wish me luck!
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