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10-22-2010, 05:51 AM   #1
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Canon FD 85mm F1.2 S.S.C. Aspherical on Pentax

I'm still waiting for my two Canon FD to Pentax PK adapters, but this won't prevent me from just holding the lens in front of my old *ist DS.

Why two adapters? I'm not keen on the regular adapter, which has a corrective element to maintain infinity focus. So I'll remove the element from the second one; hopefully I'll still be able to use it for portraits then.

Anyway; it's pretty much my only option to have a ~85mm lens with a F/1.2 speed on my Pentax



10-22-2010, 05:56 AM   #2
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Note with respect to removing the glass from the adaptor.

the adaptor is about 14mm thick, and since the canon regestry distance is already 3mm less than pentax you will be adding the equivelent of a 17mm extension tube in front of the lens.

As a result, on an 85mm lens I would expect you will be limited to a focusing range of 350 to 500mm

that is 14 to 25 inches for the metric impared.

It is a little close for portraits.

with the adaptor, and I have one, you can expect this lens to optically perform as a 125mm F1.7 lens.

that will be the best bet for you short of taking the lens apart and making it a preset.
10-22-2010, 06:08 AM   #3
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QuoteOriginally posted by Lowell Goudge Quote
Note with respect to removing the glass from the adaptor.

the adaptor is about 14mm thick, and since the canon regestry distance is already 3mm less than pentax you will be adding the equivelent of a 17mm extension tube in front of the lens.

As a result, on an 85mm lens I would expect you will be limited to a focusing range of 350 to 500mm

that is 14 to 25 inches for the metric impared.

It is a little close for portraits.

with the adaptor, and I have one, you can expect this lens to optically perform as a 125mm F1.7 lens.

that will be the best bet for you short of taking the lens apart and making it a preset.
Thanks for your reply and the information. Currently I'm investigating all my options to be able to mount this lens to my Pentaxes. Never mind the FD mount. Based on the adapters I've bought I will look at my options. I know that I can have the lens converted to EF mount, but that won't make it more usable for me

One thing though: the lens will always be a preset, regardless of the option I choose (adapter, EF conversion or PK conversion).
10-22-2010, 06:17 AM   #4
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QuoteOriginally posted by Asahiflex Quote
Thanks for your reply and the information. Currently I'm investigating all my options to be able to mount this lens to my Pentaxes. Never mind the FD mount. Based on the adapters I've bought I will look at my options. I know that I can have the lens converted to EF mount, but that won't make it more usable for me

One thing though: the lens will always be a preset, regardless of the option I choose (adapter, EF conversion or PK conversion).
it is one of the reasons I bought the adaptor, I thought if I happened across a good canon lens I might just take it if the price was right.

It is a tough call to canabalize a lens like this. as it does have some value.

10-22-2010, 06:28 AM   #5
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the only way to effectively use this lens without the corrective element is to use it on either m4/3 camera or mirrorless APS-C body.

the downfall of the optical adapter is the loss of contrast and sharpness, although you can correct these during post-processing. a halo/hazy effect around the subject especially under bright conditions and at wider apertures would also appear in situations such as that. it could be caused by low contrast and lack of correction for aberrations. oh and their will also be an increase in the DOF.

it's too bad that we can't have an effective glassless adapter for the K-mount and the only way to use such FD lenses is to do a lens mount conversion.

anyway, Peter, is the S.S.C. your own old copy or you just bought it recently? those lenses are still pretty much hold value til today.
10-22-2010, 06:28 AM   #6
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QuoteOriginally posted by Lowell Goudge Quote
it is one of the reasons I bought the adaptor, I thought if I happened across a good canon lens I might just take it if the price was right.

It is a tough call to canabalize a lens like this. as it does have some value.
Well, my copy is very used (and even has numerous scratches on the front element) but as we all know (well...) scratches on the front element are not at all that important. The back element is like new though.

I'd rather not have it converted, but who knows... There might be a FF EVIL camera in the future and suddenly it becomes completely usable again.
10-22-2010, 06:31 AM   #7
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QuoteOriginally posted by Asahiflex Quote
I'd rather not have it converted, but who knows... There might be a FF EVIL camera in the future and suddenly it becomes completely usable again.
but the conversion won't impact that. it will still be a preset.

All EVIL and for that matter 4/3 adaptors , and I think this applies to all adaptors from a long regestry distance to a shorter one, are Manual aperture only adaptors. None offer automatic aperture,
10-22-2010, 06:35 AM   #8
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QuoteOriginally posted by Pentaxor Quote
the only way to effectively use this lens without the corrective element is to use it on either m4/3 camera or mirrorless APS-C body.

the downfall of the optical adapter is the loss of contrast and sharpness, although you can correct these during post-processing. a halo/hazy effect around the subject especially under bright conditions and at wider apertures would also appear in situations such as that. it could be caused by low contrast and lack of correction for aberrations. oh and their will also be an increase in the DOF.
Indeed and that's why I'd rather not use a corrective adapter. But It was cheap enough to just give it a try. I can always resell it if I don't like it.

QuoteQuote:
it's too bad that we can't have an effective glassless adapter for the K-mount and the only way to use such FD lenses is to do a lens mount conversion.
That's why I'm hoping that there will be a FF EVIl camera in the future. Such a camera will be able to accept a VERY wide range of lenses including this one. So converting it is not on top of my list at the moment.

QuoteQuote:
anyway, Peter, is the S.S.C. your own old copy or you just bought it recently? those lenses are still pretty much hold value til today.
I bought it second hand more than a year ago. Cheap enough (less than 200 euros) because of its less-than-ideal condition, though it's still very good optically.

10-22-2010, 06:37 AM   #9
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QuoteOriginally posted by Lowell Goudge Quote
but the conversion won't impact that. it will still be a preset.

All EVIL and for that matter 4/3 adaptors , and I think this applies to all adaptors from a long regestry distance to a shorter one, are Manual aperture only adaptors. None offer automatic aperture,
Sorry, I was not clear enough: for me a preset aperture is the same as "completely usable again". I would not mind that my old PK glass is preset on such a camera, as long as I can still use them on the format they were intended to.

Now that I think of it: having your lenses stopped down all the time is not a problem on any EVIL camera. You'll even see the DOF in real time.
10-22-2010, 06:41 AM   #10
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Looks like just holding the lens in front of your old *ist DS isn't all that bad either.

Great shot!

I can't find the post now, but somebody else on this forum converted one to Pentax, but infinity was pretty short (wow, that sounds weird).
10-22-2010, 06:50 AM   #11
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QuoteOriginally posted by farfisa Quote
Looks like just holding the lens in front of your old *ist DS isn't all that bad either.

Great shot!

I can't find the post now, but somebody else on this forum converted one to Pentax, but infinity was pretty short (wow, that sounds weird).
I think I saw the post.

the problem is that if you do not make measurements and really go after all the excess material you can there is just no way to claw back the 3.46mm needed to retain infinity focus on a pentax camera.

the FD regestry distance is 42mm against pentas's 45.46mm.

I have managed with minolta MD lenses to achieve infinity focus by removing the mount, a spacer or two, and surface grinding some parts a little, and using a flanged adaptor which is quite thin, compared to a regular lens mount to retain infinity focus, but that is dealing with only a 1.8mm difference in regestry distance, not 3.46mm as it would be on canon.

what I would really love, would be for a reputable lens maker, to really look at this and offer well designed multi coated mount converters, although in controlled conditions the cheap ones do work pretty well, just avoid strong light / high contrast, and wide open, at least from my experience.
10-22-2010, 07:52 AM   #12
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QuoteOriginally posted by Lowell Goudge Quote

what I would really love, would be for a reputable lens maker, to really look at this and offer well designed multi coated mount converters, although in controlled conditions the cheap ones do work pretty well, just avoid strong light / high contrast, and wide open, at least from my experience.
the only way to do that is to add more elements for enhancements and to correct for aberrations. by doing this, infinity focus might become a problem.
10-22-2010, 08:10 AM   #13
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QuoteOriginally posted by Pentaxor Quote
the only way to do that is to add more elements for enhancements and to correct for aberrations. by doing this, infinity focus might become a problem.
Yes, adding more elements is true, but infinity focus is not an issue. the present adaptos already make use of the additional space that is mechanically required to acept the different mounts by placing corrective lenses (really a small telephoto group) into the adaptor. The only question is, how thin, and / or how little magnification is possible in the space.

Note, My sigma 1.4x is only 20mm thick.
10-22-2010, 08:44 AM   #14
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QuoteOriginally posted by Asahiflex Quote


I bought it second hand more than a year ago. Cheap enough (less than 200 euros) because of its less-than-ideal condition, though it's still very good optically.
I see. the cheapest one that I saw which is in good condition is around $500. years ago they cost about $200-$400. nowadays, most of them are around $800 or more. personally IMO, I prefer the old FD 85 compared to the modern day Canon 85 in terms of rendering.
10-22-2010, 09:30 AM   #15
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QuoteOriginally posted by Asahiflex Quote
Thanks for your reply and the information. Currently I'm investigating all my options to be able to mount this lens to my Pentaxes. Never mind the FD mount. Based on the adapters I've bought I will look at my options. I know that I can have the lens converted to EF mount, but that won't make it more usable for me

One thing though: the lens will always be a preset, regardless of the option I choose (adapter, EF conversion or PK conversion).
There is a thread here with links to a post where a Russian guy converted one of these to a k-mount and it appeared that he did a nice job.

https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/95710-new-pentax-85mm-1-2-a.html


http://www.penta-club.ru/forum/index.php?showtopic=47191&hl=fd

Normally, I would say this is too damn much trouble but this is one exception.
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