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05-01-2011, 05:10 PM   #1
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Canon FD on my KR

I have the opportunity to buy a Canon FD 400mm f2.8 in excellent shape for $1000. However, obviously, the mounts are different

After searching around the forums here, I think I've found what I need to make the Canon fit my Pentax. Just wondering if anyone has any experience with these:

Canon FD Lens to Pentax PK Focus to Infinity Adapter US on eBay.ca (item 110637895978 end time 19-May-11 05:33:21 EDT)

I understand that I will lose quality because of the correcting lens in the adapter, but really, on a lens as sweet as the FD 400mm 2.8, I think the quality will still be very acceptable.

05-01-2011, 06:20 PM   #2
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The adapter will turn it into a 568mm f/5 with a lot of flare wide open.
05-01-2011, 07:22 PM   #3
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I don't have any experience with the adapter in question. And in general, I'm not a fan of lens adapters.

It looks like the adapter has a single optical element. I wouldn't put much hope in it.

Also, the adapter does not have any aperture mechanism. You'll need to use the lens in total stop-down mode.
05-01-2011, 07:43 PM   #4
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Buy a used Canon body for it.

05-01-2011, 08:17 PM   #5
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QuoteOriginally posted by SpecialK Quote
Buy a used Canon body for it.
Canon DSLRs, or even Canon autofocus film cameras, are not compatible with Canon FD mount. You still need an adapter. That's the reason why FD lenses are inexpensive.
05-01-2011, 08:45 PM   #6
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How to use a Canon FD lens on a Pentax PK camera:

* An optical adapter that acts as a short teleconverter and reduces image quality.
* Major surgery -- I've adapted various lenses but there's no way I'll touch any FD.
* I'd suggest a glassless or reversal adapter for close-ups, but there's no aperture control.
* Remove the Pentax camera's PK mount; replace it with an FD mount. Good luck.
05-02-2011, 01:52 AM   #7
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Adaptation of canon FD mount for (sort of) Pentax K

Hello!

I bought an inexpensive Soligor 400mm f6.3 for Canon FD mount.

I found the information about the conversion on some russian site. Here is one link (i found some other but I cant find it now) Переделка объектива Canon FDn на Pentax - Форумы Пента-клуба so just run it through the google translator to get some idea what it is about.

Basically what I did was to remove the whole mount (since PK has some shorter distance to the film/sensor plane than FD) and cut the aperture lever (so I got the completely manual diaphragm). Then I purchased some cheap PK macro tubes from which I removed the mount on the "lens" side.

So I marked the holes on the PK mount where i had to drill in order to use the screws from the FD mount. Then what was left was to screw in the new mount to the old lens.

Finally I got a total manual 400mm f6.3 lens for Pentax. I did retain the infinity focus, although since it seems that the lens is somewhat closer to the sensor/film plane than it should be, it focuses somewhat pass the infinity (not by much). On the other hand I lost few inches on the close range, but that was nothing to worry about for a tele-lens.

Since I am a total amateur, it took me a lot of time to this conversion. So although I ended up with a total working lens if you ask me whether it was worth (in my case) my answer would be no. Would I recommend somebody to do it, well it depends. If you can find a decent prime and get the conversion done professionally then it can be worth it. However you'll end up with a completely manual lens.
05-02-2011, 12:23 PM   #8
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As others have noted, there is no adaptor to use this lens without upsetting infinity focus, and this includes canon, where there were some mechanical adaptors made when they initially changed over, but these also cost infinity focus.

I have the FD to K adaptor, which converts the lens into a completely manual aperture lens.

The adaptor does add some problems to the image, especially when wide open , the lens exhibited color blooming (usually in the white range) as well as loss of definition, but stopped down the lens worked acceptably. Note i tried this only with a 50mm F1.8 (effectively the canon kit lens of the time which was not the greatest to start with)

If you get the adaptor it is cheap, and it would be worth a try on the lens assuming you can try it first.

Otherwise, surgery is required to change mounts, and this requires a serious amount of mechanical understanding, as well as control of the metal parts thickness you remove, so you can claim back about 3 mm of material to retain infinity focus. This is not a job for the faint-hearted, when hacking up a $1000 lens

05-02-2011, 03:26 PM   #9
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Thanks very much guys. The decision is to leave it be and hope Pentax makes a 400mm f5.6. This way I can get to 400mm on a budget
05-02-2011, 03:43 PM   #10
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400mm f5.6

Tokina makes a 400mm f5.6 auto focus, I have one and have thought about selling it. . . . if you are interested then just simply change the name on the check you were going to give to that canon fellow to my name and we can proceed!
05-02-2011, 03:57 PM   #11
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QuoteOriginally posted by calculator01 Quote
Thanks very much guys. The decision is to leave it be and hope Pentax makes a 400mm f5.6. This way I can get to 400mm on a budget
I bet, on a slightly larger budget than you plan. It would make sense for that lens to have same features and price level of the 200/2.8 and 300/4.
05-03-2011, 02:37 AM   #12
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QuoteOriginally posted by calculator01 Quote
I have the opportunity to buy a Canon FD 400mm f2.8 in excellent shape for $1000. However, obviously, the mounts are different

After searching around the forums here, I think I've found what I need to make the Canon fit my Pentax. Just wondering if anyone has any experience with these:

Canon FD Lens to Pentax PK Focus to Infinity Adapter US on eBay.ca (item 110637895978 end time 19-May-11 05:33:21 EDT)

I understand that I will lose quality because of the correcting lens in the adapter, but really, on a lens as sweet as the FD 400mm 2.8, I think the quality will still be very acceptable.
Welcome to https://www.pentaxforums.com/forums/pentax-camera-field-accessories/96884-ada...addiction.html


Both me and Pentaxor have been testing that adapter in this thread.

It is not that bad for such a simple converter.
It is easy to remove the glas element. That gives you an adapter without infinity buth which work for macro applications without any optical degradation, and with apperture controle.
05-03-2011, 05:32 AM   #13
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Actually, in thinking about it a little, a no glass adaptor may make sense for a lens like the 400mm.

When I use my long lenses, it is rarely at infinity, so loss of infinity focus is not an issue.

given the focal length and the thickness of the adaptor at about 8mm this would give you about 20meters (65 feet) as maximum focus. Unless you are shooting hawks, most birds need to be that close to get a good shot any way.
05-03-2011, 09:15 AM   #14
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Yep, and the Canon FD 400/2.8 have a hell of a reputation. I've been dreaming about it myself. At least it is more realistic that I'd be able to afford that than the SMC Pentax-A* 400/2.8.

Calculator, if you get it, please post something with it in the adapter thread.
05-03-2011, 12:03 PM   #15
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QuoteOriginally posted by SOldBear Quote
Canon DSLRs, or even Canon autofocus film cameras, are not compatible with Canon FD mount. You still need an adapter. That's the reason why FD lenses are inexpensive.
Ah, bummers.
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