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12-20-2008, 01:33 PM   #1
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Practical to modify original FD to Pentax?

Is it practical to modify an original Canon FD to Pentax K manual?

The FD would need to be trimmed by about 3.5mm. Is there that much length availible in the FD's silver knurled connector thing?

12-20-2008, 04:16 PM   #2
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Переделка объектива Canon FDn на Pentax - Форумы Пента-клуба
12-20-2008, 04:27 PM   #3
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Done by KGB?
12-20-2008, 04:30 PM   #4
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you may find the register distance is too short for it.

12-20-2008, 04:32 PM   #5
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I can't read the Russian text but the pictures show success.

Also I was sent this link about conversion to an EOS mount.
Dynamic Miscellany : Canon 55mm f1.2 FD -> EOS Conversion

I ordered a modest FD to experiment with.
12-20-2008, 05:39 PM   #6
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QuoteOriginally posted by roentarre Quote
you may find the register distance is too short for it.
James is right. You would need to find a way to shift the entire optical assembly in order to compensate for the registration distance difference. If you don't do that, you'll end up with a lens that focuses beyond infinity.
12-20-2008, 05:55 PM   #7
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I have the Tamron Adaptall-2 mounts for Pentax PK, PK/A, EOS-M, and FD but I have never tried to do any measurements.
12-20-2008, 05:59 PM   #8
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QuoteOriginally posted by newarts Quote
Is it practical to modify an original Canon FD to Pentax K manual??
Short answer: No. Seems it'd be lots of effort and/or expense for each & every lens you have. For the money you can likely get better performing manual Pentax lenses that can be had for very little.

Can it be done? Yes, and as you've seen, it has been done. The question is why would you?

Looking at those pictures, most notably the kittens, the highlights get blown out. I think you'd be better off with some trusty old Pentax glass.

12-20-2008, 06:04 PM   #9
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I agree with Tour de Force. If you want to convert some cool glass from another maker, look into some of the Leica R stuff with a Leitax mount. Leica & Pentax | Leitax I just found out about them this week from some other PF members.
12-20-2008, 06:07 PM   #10
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QuoteOriginally posted by TourDeForce Quote
Short answer: No. ....

Can it be done? Yes, and as you've seen, it has been done. The question is why would you?...

... I think you'd be better off with some trusty old Pentax glass.
I enjoy doing such things and I'm poor.

I'd love to get a Pentax or Zeiss 200/2.8 for $100 or so.. Can you point me to one?

Dave
12-20-2008, 06:17 PM   #11
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QuoteOriginally posted by newarts Quote
I enjoy doing such things and I'm poor.

I'd love to get a Pentax or Zeiss 200/2.8 for $100 or so.. Can you point me to one?

Dave
I have a 200mm f/4 Takumar for you in that price range. Will that do? Fabulous color & holds the highlight detail...
12-20-2008, 06:22 PM   #12
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QuoteOriginally posted by TourDeForce Quote
I have a 200mm f/4 Takumar for you in that price range. Will that do? Fabulous color & holds the highlight detail...
Thanks, I have one. I agree it is a nice lens.
12-27-2008, 09:06 PM   #13
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FD to Pentax

I think I can speak from experience (somewhat).
The longer canon lenses have enough space after the rear element to allow for some "trimming" of the mount. I use a Canon SSC 400/4.5 Breech Lock lens that was my main birding lens on the k100D till I got a Tamron 300/2.8. I can not take credit for the conversion. The 400/4.5 was already converted to
Nikon Mount by the previous owner so I just needed to replace the mount. It works great (preset aperture only) and focuses correctly to infinity. I did look for other FD/FL glass to convert but found that the more desirable glass (like the 85/1.2, 55/1.2 etc.) just don't have enough space.

I also think that the Takumar's are a much better choice if what you want is "cheap but great" optics.

Just my 2 cents on this topic

Last edited by lynch1234; 12-29-2008 at 08:59 PM.
12-28-2008, 09:00 AM   #14
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QuoteOriginally posted by lynch1234 Quote
I think I can speak from experience (somewhat).
The longer canon lenses have enough space after the rear element to allow for some "trimming" of the mount. ...
Thanks. The situation is getting clearer to me.

I got a 50mm 1:1.8 FD to look into conversion. It appears that the conversion of this lens may be possible without machining but it is a very close call. The len's rear element may protrude too far and interfere with the camera's mirror. In addition, it probably isn't possible to get infinity focus without a little machining. However, without machining, infinity focus is almost possible and may be "good enough".

Light sealing to complete the conversion looks to be a step difficult to achieve in an acceptable way (unless black tape is acceptable or black rubber tubes of just the right diameter can be found.)

In summary it is looking like conversion of FD's to K's might be practical in some cases and impractical in others.

On the other hand, it looks like Nikon-F to Pentax-K conversion is straightforward, so I've purchased a Soligor 200mm 1:2.8 and am eagerly awaiting its arrival to attempt the conversion. (The Nikon-F flange distance is 1.04 mm longer than the Pentax-K, so just replacing the F flange with a K flange should be sufficient.)

Thanks for your help,
Dave
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