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04-07-2010, 09:58 AM   #1
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Canon FD to Pentax conversion questions

I'm bored, so I want to find a way to get revenge for all those canon users stealing and butchering our old M42 lenses

What I'm looking to replicate is this: Dynamic Miscellany : Canon 55mm f1.2 FD -> EF Conversion Someone ripped apart an old FD canon and fixed it up to mount on the EF bodies. The FD is 42mm, and the EF is 44mm, but he had to extend his mounting device by at least enough to allow for the 45.5mm that exists on a Pentax. I'd also be willing to shave down any bits I need to in order to make this work. We don't need the AF confirm indicator in there either so it's just a mechanical conversion.

So before I go out and buy two lenses to rip apart and mash together, I've got a few questions.

First off, how does the shutter work on a canon? Is it a leaver / leaverlike mechanism? Does whatever mechanism there work the same as the Pentax (pressure opens, lack of pressure closes). And I guess, obviously, has anyone tried this before and made it work?

Any other technical bits I should be aware of before I try this?

04-07-2010, 10:09 AM   #2
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there is a post where someone has converted a 300mm F2.8 FD lens to PK, and retained automatic stop down,

It does seem possible, buit you need to be brave.

there is also now on the market for both canon FD and nikon AI lenses optical converters that convert these lenses into stopdown metering PK mounts.

I have tested the Nikon one, and effectively it is a 1.25x TC (the optical elements and magnification allow the lens to retain infinity focus, and the cost of 1/2 stop and 25 % change in focal length.

As a result, it is really useful on normal to tele lenses.

I have the canon version on order and will post the performance when I get it (and pick up a cheap 50mm FD lens to test with it.)
04-07-2010, 10:18 AM   #3
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How much do these adapters cost, and how's the overall quality of them?
04-07-2010, 10:21 AM   #4
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Also, if anyone has that post, I wouldn't mind it being PM'ed or posted.

04-07-2010, 10:24 AM   #5
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QuoteOriginally posted by whelmed Quote
How much do these adapters cost, and how's the overall quality of them?
they cost about $40,

I have not done extensive testing but spent a day in a greenhouse with an AI Nikor 50mm F1.8 and the adaptor, which made it a 62mm F2 lens.

here is a sample



pretty good actually, but note my K10D is set up for MF including a diagonal split image focusing screen with microprism collar
04-07-2010, 10:57 AM   #6
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This thread has links to the FD to K converter.

https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/95866-fd-k.html
04-07-2010, 11:37 AM   #7
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I just finished a FD L 2.8/300m conversion and at least with this lens I was able to turn it into a K-mount lens with open aperture focusing. It closes the aperture when taking a shot with a lever very much like the on found in K-lenses. I've posted something about it in The Impossible Lens Club.
04-07-2010, 12:32 PM   #8
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QuoteOriginally posted by ovim Quote
I just finished a FD L 2.8/300m conversion and at least with this lens I was able to turn it into a K-mount lens with open aperture focusing. It closes the aperture when taking a shot with a lever very much like the on found in K-lenses. I've posted something about it in The Impossible Lens Club.
I guess the question I have is, how typical is the mechanical assembly you took apart, with respect to other FD mount lenses.

04-07-2010, 12:58 PM   #9
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If you can translate this thread from Russian . . .


Переделка объектива Canon FDn на Pentax - Форумы Пента-клуба
04-07-2010, 01:37 PM   #10
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QuoteOriginally posted by Blue Quote
Can't read a damm word of it, but the photos seem to be multi lingual

The photos however, do not show the conversion I am talking about, but a conversion from FD to K with stop down metering, not FD to K with auto stop down but open aperture focusing.
04-07-2010, 05:52 PM   #11
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Wow - this is what I've been dreaming about. Got old FD stuff that is going to waste.

QuoteOriginally posted by Lowell Goudge Quote
they cost about $40,

I have not done extensive testing but spent a day in a greenhouse with an AI Nikor 50mm F1.8 and the adaptor, which made it a 62mm F2 lens.

here is a sample...<snipped>

pretty good actually, but note my K10D is set up for MF including a diagonal split image focusing screen with microprism collar
Pretty good image! Thanks for showing us the capability!

QuoteOriginally posted by Lowell Goudge Quote
Can't read a damm word of it, but the photos seem to be multi lingual

The photos however, do not show the conversion I am talking about, but a conversion from FD to K with stop down metering, not FD to K with auto stop down but open aperture focusing.
Its a really interesting article - even with Google translate. Trouble is you need a lathe and good metal work skills IMHO

QuoteOriginally posted by boriscleto Quote
Had a look at that - not bad price - even in AUD$. I've got a stack of macro stuff I'd love to use (bellows with a great rack system on it, tubes, lenses, reversing ring). But on the other hand, I've recently picked up macro gear for Pentax (tubes, lens)

Not sure if my other stuff is worth it - but for AUD$40 its almost worth the punt.

Then again, it might be possible to pick up old FD tele lenses (FD 300mm etc) for next to nothing.

Hmmmmmmm
04-09-2011, 05:22 PM   #12
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I have posted a few pointers for such conversion in the following thread:

https://www.pentaxforums.com/forums/lens-clubs/64271-impossible-lens-club-9.html

This is a basic (but fully reversible) conversion that works well in AV and M modes on Pentax cameras.


QuoteOriginally posted by whelmed Quote
I'm bored, so I want to find a way to get revenge for all those canon users stealing and butchering our old M42 lenses

What I'm looking to replicate is this: Dynamic Miscellany : Canon 55mm f1.2 FD -> EF Conversion Someone ripped apart an old FD canon and fixed it up to mount on the EF bodies. The FD is 42mm, and the EF is 44mm, but he had to extend his mounting device by at least enough to allow for the 45.5mm that exists on a Pentax. I'd also be willing to shave down any bits I need to in order to make this work. We don't need the AF confirm indicator in there either so it's just a mechanical conversion.

So before I go out and buy two lenses to rip apart and mash together, I've got a few questions.

First off, how does the shutter work on a canon? Is it a leaver / leaverlike mechanism? Does whatever mechanism there work the same as the Pentax (pressure opens, lack of pressure closes). And I guess, obviously, has anyone tried this before and made it work?

Any other technical bits I should be aware of before I try this?
04-09-2011, 06:14 PM   #13
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about a year ago I did convert a Canon FD 85mm f/1.2 to pentax K mount, it does passably well though though my FA*85mm f/1.4 wipes the floor with it optically. It was a fun experiment.
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