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10-26-2012, 01:21 AM   #1
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Convert Tokina mirror lens to k-mount ?

I have just picked up a very nice Tokina 500 mirror lens for $20 but it has a Minolta P-mount (I think)......is there any way of converting this mount to a K-mount ? I was hoping to buy a fixed K-mount I could simply screw on in the Minolta mount's place ?

10-26-2012, 01:53 AM   #2
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I haven't converted any Minolta lenses myself, but if you take a look in the "impossible lens club" there is probably someone who has done it and given some hint. I bet RioRico tried it.
10-26-2012, 03:04 AM   #3
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Is it a fixed mount or a T2? Very often these lenses were produced with a standard T2 screw mount and a camera specific mount then added, similar to the Tamron Adaptall system.

If T2, all you'll need to do is source a Pentax T2/K mount, remove the existing mount and replace it with the Pentax one. The clue to T2 is normally three little screws inset into a knurled ring that forms part of the mount itself.

Here's an example; T2 Mounts
10-26-2012, 04:32 AM   #4
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Be careful converting this lens as they usually have a rear filter that screws into the mount. With-out these filters the lens won't focus properly.
This is a Tokina 500 mirror with a P/K mount and you can see the filter screwed into the mount.
Glenn

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10-26-2012, 07:32 AM   #5
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Pictures would help. The Minolta SR/MD mount has a shorter register than Pentax (43.72 vs 45.46mm). This may not be a problem as many mirror and super telephoto lenses focus beyond infinity (!) to allow for thermal expansion and contraction. There are glassless Minolta MD to K mount adapters but they add about 5-10mm so you normally lose infinity focus.

There is this thread on modifying Konica and Minolta mounts to Pentax but it involves machining. Mind the caution about keeping the rear filter threads of this lens intact.

https://www.pentaxforums.com/forums/pentax-lens-articles/56234-konica-minolta...ld-lenses.html

If you know someone with a lathe (preferably a computer controlled mini-lathe) they might be able to duplicate the mount from G and T's lens (given the proper dimensions and measurements). It looks like the register differences are made up in the base of the mount so they may just be interchangeable since there are no aperture controls to fuss with.
10-26-2012, 10:20 AM   #6
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It's a fixed mount, unfortunately.
10-26-2012, 10:23 AM   #7
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It has M/XG engraved into the face of the mounting flange. I see the filter mount now - hadn't figured out where it went - actually thought it may somehow fit into the nameplate on the front of the lens !
10-26-2012, 10:29 AM   #8
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I was so hoping I could simply buy a P/K mount somewhere - as in the pic from G & T ?

10-26-2012, 05:27 PM   #9
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I doubt you would be able to buy a replacement mount from Tokina. You might be able to add a spacer or machine down to a mount cannibalized from a K-Mount teleconverter or broken lens. You might be able do the same with a third party something to PK mount adapter. You'd need to know the measurement of the distance from the base of the lens to the base of the flange on G & T's lens. This assumes the base of the lens is the same - it may not be.
10-26-2012, 06:53 PM   #10
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QuoteOriginally posted by Not a Number Quote
I doubt you would be able to buy a replacement mount from Tokina. You might be able to add a spacer or machine down to a mount cannibalized from a K-Mount teleconverter or broken lens. You might be able do the same with a third party something to PK mount adapter. You'd need to know the measurement of the distance from the base of the lens to the base of the flange on G & T's lens. This assumes the base of the lens is the same - it may not be.
If there are any dimensions you wish to know,please ask and I will try to get to you ASAP.
Glenn
10-27-2012, 04:25 AM   #11
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Thanks for the advice Glenn.....it looks as though it would be a better option to just sell it and keep on looking for a better deal.
10-27-2012, 03:45 PM   #12
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QuoteOriginally posted by jamesw Quote
Thanks for the advice Glenn.....it looks as though it would be a better option to just sell it and keep on looking for a better deal.
They are quite common in K mount and regularly pop up on ebay, good luck finding one.
Glenn
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