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04-04-2012, 04:32 PM   #1
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Using Pentax DSLR with Canon FD Lenses -- Is It Possible?

I'm not sure if this question belongs here or in a lens forum, but here goes...

Has anyone used Canon FD lenses with Pentax digital SLRs? If so, what adapters and accommodations have to be made?

Here's the back story: I want to try and convince a friend to consider a used Pentax DSLR, not because I want to sell him one, but because there are some good older models that can be had inexpensively. He's reluctant to take the plunge and buy a Canon DSLR, in part because of the expense, and because someone told him he can't use his older lenses with the digital Canon bodies. (He owns an old Canon film camera and a couple lenses. Apparently those lenses are FD mounts.)

I don't know whether or not his information is correct, but it did give me an idea. I think he'd give modern cameras a try if he could use those old lenses. If he could use the old lenses on a Pentax digital body -- say a K10D, K20D, or K200D -- then he might be persuaded to give Pentax a go. My argument to him would be the quality of the Penny body, along with the many used lenses which could be bought relatively inexpensively as he dips his toe into the DSLR waters.

Any ideas?

04-04-2012, 04:55 PM - 1 Like   #2
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Unfortunately, the distance between the lens and film/sensor is shorter on FD mount than K mount. This means you need an adapter with glass in it to correct the difference - most people think it's not worth the image quality loss. You could mount them on something with an even shorter focal distance, for example, micro four thirds or Leica M mount.
04-04-2012, 04:58 PM   #3
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QuoteOriginally posted by jeztastic Quote
Unfortunately, the distance between the lens and film/sensor is shorter on FD mount than K mount. This means you need an adapter with glass in it to correct the difference - most people think it's not worth the image quality loss. You could mount them on something with an even shorter focal distance, for example, micro four thirds or Leica M mount.
Ah, I see. So it's not entirely a lost cause to hope to reuse the old lenses, but just not very likely with Pentax bodies. Oh well. I'll try to encourage him to go with a used Pentax anyway. Thanks, Jez!
04-04-2012, 05:17 PM - 1 Like   #4
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This has been discussed many times before - and the results are variable. You can see people have used all sorts of lenses. The downside is variations in quality.

Have a look at this thread: https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/96625-canon-fd...tml#post983862

As an aside (and off topic to a certain extent) I've managed to mount a Canon FD auto bellows to my K200D with a K to Tmount adapter + Tmount to FD adapter. Works ok - just need better glass in front. I'm thinking of microscope objectives or enlarger lenses.

Cheers

04-04-2012, 05:20 PM   #5
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QuoteOriginally posted by MoiVous Quote
This has been discussed many times before - and the results are variable. You can see people have used all sorts of lenses. The downside is variations in quality.

Have a look at this thread: https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/96625-canon-fd...tml#post983862

As an aside (and off topic to a certain extent) I've managed to mount a Canon FD auto bellows to my K200D with a K to Tmount adapter + Tmount to FD adapter. Works ok - just need better glass in front. I'm thinking of microscope objectives or enlarger lenses.

Cheers
Thanks much for the link, Chris! I must have used bad search terms. Your jury rig sounds doable, but I can see it would be rather involved, perhaps too much so for my friend. Even so, I'll pass it on to him. Much appreciated!
04-04-2012, 05:40 PM - 1 Like   #6
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Yes, alas, the short answer is NO.

The long answer is: Canon FD lenses *can* be used on Pentax dSLRs, but only with severe limitations or much delicate work. They're almost never worth the trouble.
___________________________________

As jeztastic pointed out, the flange-focal-distance aka register is longer for Pentax than Canon FD. That means that, even if a Pentax mount were put on a C/FD lens, the lens would not be able to focus to infinity. So to be usable, an optical adapter is necessary. This acts as a short teleconverter -- the lens becomes longer, slower, and loses some IQ. If the lens was special before, it won't be afterwards.

A C/FD lens could be used for close or macro work, where infinity doesn't matter, but that's rather limiting, and there are mechanical interface problems; the aperture mechanism has a difficult design. That's why we don't see (m)any non-optical FD-PK adapters sold on eBay.

Another way to handle the register difference is to shorten the C/FD lens by about 3.5mm: chop-off the base of the lens. Unfortunately, most Canon lenses have rather important mechanisms and optics down there. Some third-party FD-mount lenses *could* be chopped, but only by someone with machine-shop tools and skills. I've modified other types of lenses; I won't go near FDs.

The other possible way is to reverse the lens and use it only for macro work. There are still problems with working the aperture. (Many folks consider the C/FD mount as among the worst ever designed.) Rather than reverse and/or adapt Canon lenses, I just sold what I had.
___________________________________

So, there are many good reasons for switching to Pentax, but C/FD compatibility ain't one of them.

Last edited by RioRico; 04-04-2012 at 06:46 PM.
04-04-2012, 05:44 PM   #7
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Thanks ever so much for the detailed reply to my questions, RioRico. If it was me, given what you said, I'd just get rid of my Canon system and go Pentax all the way. I'll see if I can convince my friend to do just that. I doubt he would be willing to go to the kind of trouble needed to modify the FD lenses. Thanks again!
04-04-2012, 06:46 PM   #8
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I think a lot of us use Pentax because it is so easy to use the older glass. Other brands vary from impossible to just difficult. Certainly it has been one of the strong points for the Pentax brand.

It sounds like your friend might be a tough sell either because he doesn't want the expense or has some attachment to his old glass. Or maybe he is just not ready to move to digital.

My father was using an old Konica film camera and I finally convinced him he needed to move to digital. Which he did, in his usual manner, by listening carefully to me and others recommend Pentax and then going to Best Buy and letting the sales people talk him into the cheapest Canon they had on the shelf. But I digress.

The real problem is that now he has a digital camera, and has no idea how to get the pictures into a usable form. So the camera sits on the shelf and it was essentially money wasted. The moral of the story is that if your friend is not ready to move to digital and the technology required to support digital processing he might just be better off with film.

04-04-2012, 06:53 PM   #9
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QuoteOriginally posted by Tamia Quote
Thanks ever so much for the detailed reply to my questions, RioRico. If it was me, given what you said, I'd just get rid of my Canon system and go Pentax all the way. I'll see if I can convince my friend to do just that. I doubt he would be willing to go to the kind of trouble needed to modify the FD lenses. Thanks again!
As jeztastic mentioned, C/FD lenses can conceivably be used on shorter-register cameras like Leica M (or the Ricoh GXR M-mountor), 4/3 or m4/3, Samsung NX, Sony NEX, even the Nikon A and Pentax Q -- though I don't know if FD adapters are available for all those. But modifying FD lenses is just too intricate for the vast majority of us. Your friend might be best off with a GXR, NEX, or m4/3 system. Cheers!
04-05-2012, 03:47 AM - 1 Like   #10
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There is an adaptor that can be used to mount canon FD lenses to Pentax cameras. The adaptor comes in two variants, optically compensated or not.

The optically compensated adaptor corrects for the change in registry distance and provides for infinity focus, but at the cost of adding a 1.45x magnification (like a tele counter) therefore it works fine for longer lenses but it's benifit is lost on shorter lenses.

The non optically compensated adaptor is identical but without the optics, and acts like a 14mm extension tube, meaning it can't be used at all for wide angle lenses except for extreme, close up, or for moderate macro with longer lenses.

Canon is the worst manufacturer, having abandoned its lens out not once but twice. Additionally from the use of canon lenses perspective, is the hardest to deal with due to the shortest system registry of any SLR.

But the one redeeming benifit of canon today, is that the lens mount they presently use, when combined with the short system registry, make it possible for canon users to, within the limits of manual focus and exposure control, use lenses from virtually any other film cama with simple adaptors
04-05-2012, 04:16 AM - 1 Like   #11
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There is an adapter from FD to K that you can find on ebay. I use it together with the Canon FD 200mm macro 1:1 f4, with some success. The adapter comes with glass, which works like a not so good converter, so it increase the focal length. It is easy to unscrew the glass from the adapter, in which case you lose infinity. The longer focal length you have, the further away you can focus. With the adapter glass-free, the 200mm macro can focus to about 2.5m, and when shooting bugs, butterflies etc. that is plenty enough. I've used it both with and without glass, but prefer it without glass, though the optical degradation with the glass is less than I expected.

See the adapter thread for more info on the adapter and to see it used with some lenses: https://www.pentaxforums.com/forums/pentax-camera-field-accessories/96884-ada...addiction.html

Here is some example: https://www.pentaxforums.com/forums/post-your-photos/109536-macro-butterflies...1-1-macro.html

I think the reason that the FD mount is so mechanically complex and different to other mounts is that it enables both Av and Tv without any electronical contacts. Other brands added some sort of electronical contacts to get that, which allowed them to keep the mount simpler. The FD mount was built for that already before they had any camera with both Av and Tv, a carefully kept secret. But I may be wrong. It is certainly different.

EDIT: At least when I bought it you could not get the version without optics for Pentax K (but for Nikon F), but it was easy to remove the optics. Reversible procedure, just unscrew.
04-05-2012, 04:40 AM   #12
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Thanks very much Lowell and Douglas. I have plenty of useful info to pass on to my friend. I've sure learned a great deal about this subject from you all. Those macro photos might just sway him, Douglas, since I one of his lenses is a macro. Thanks again, folks!
04-05-2012, 05:30 AM   #13
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QuoteOriginally posted by Tamia Quote
Thanks very much Lowell and Douglas. I have plenty of useful info to pass on to my friend. I've sure learned a great deal about this subject from you all. Those macro photos might just sway him, Douglas, since I one of his lenses is a macro. Thanks again, folks!
check the thread that douglas did on all the adaptors as I believe there are some posted shots using the canon adaptor with glass and an FD 50/1.8 lens

Optically, the adaptors are not great, and the results when shot wide open are quite soft, with a lot of color bleading at the edges, they sharpen up very nicely by about F5.6 or F8 but then again any cheap lens can be reasonably sharp at those apertures.

The extension for macro is a good thing to consider, since macro is best done with manual focus any ways, and therefore it will not be a great issue to use the canon macro, but look at the performance wide open too, using the optical correction as it can be useful creatively for portraits, as it is very soft. For $30 (it htink i paid, it is worth it top play with)
04-05-2012, 12:06 PM - 1 Like   #14
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One thng to consider - if these are great lenses, then compromising them with an adapter is probably not an acctable solution. But I suspect it'sjust as likely we're talking about the FD equivalent of the M50/2 here - very mediocre lenses that can be replaced for under $99 on the dozen. And hence, very probably not really something that should factor into the decision either way.
04-05-2012, 01:35 PM - 1 Like   #15
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The Canon FL/FD lenses have their own character. Here in my second (or third) childhood I've been going back to my roots, both with screw-mount Pentax and then found a Canon FT like I got when they first came out. After doing a full CLA on the body and 50 1.4 FL (sluggish diaphragm - just like mine developed in '68) I went out shooting both and was surprized at the images from the FL 50 1.4 (2nd version). Higher contrast than the ST 1.4, and very vibrant images. I've also been comparing the Canon FL 55 f1.2 and SMC Pentax-K 50 f1.2, and the Canon again seems a bit more pleasing. Of course, Canon had a longer history of fast lens designs going back to their rangefinder days, while Pentax came late with their 1.2.
The Canon FL lenses are also very nice mechanical designs, which is what lured me to Canon in '67 instead of staying with Pentax and moving to Spotmatic.
But I've always preferred Pentax bodies. My Canons back then had an annoying (but musical) "ping" after each shot - which is why I next moved to Leica.
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