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11-08-2011, 03:48 PM   #1
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Stupid P/K-A mount question

I am a bit confused about the P/K-A mount and adaptor needed. Back in the day I had a Ricoh XRM and an assortment of Pentax mount manual lenses. They've all been sitting on the shelf in hibernation until recently when I got back to SLR's with the K20. The only lens with an "A" setting was a Vivitar 28-85, so of course that was the one I was most excited about trying. But it didn't fit on the Pentax body. As it turns out it was also the only one with a P/K-A mount instead of just PK. I thought they would all fit since they must have fit the Ricoh. So in searching this forum for info, the only hits for P/KA mount mentioned "Adaptall" and all the mentions of "Adaptall" were in regards to Tamron (as opposed to Vivitar or other 3rd parties). So I'm confused about what I would need to use this lens on the K20.





It is the raised plastic portion that is too long to fit. All the others have a mush shorter raised portion. Sorry for the 'thing-a-ma-jig' terminology.

So, my stupid questions ... should it have fit directly? If not, what kind of adaptor do I need, and how much should it cost? And finally, is the lens even worth the effort?

Thanks for your help.


Last edited by wzdevito; 11-08-2011 at 04:03 PM.
11-08-2011, 03:52 PM   #2
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There are some makers that did not conform to the clearance requirements and at the time they got away with I until the KAF2 mount and DSLRs. Just cut the flange off to match the Pentax lenses you have
11-08-2011, 03:52 PM   #3
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Trim the shroud to match the others. Check/search the Articles forum for discussions.

H2
11-08-2011, 04:04 PM   #4
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Before trimming anything, remove the flange (2 black screws at 3 and at 9 o'clock positions in the first photo, I think) and see how it works.

If you want to trim the flange, you'll have to remove it from the lens anyway.

11-08-2011, 04:09 PM   #5
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That was fast - thanks for the quick responses! Just to confirm, "flange" and "shroud" are both referring to what I called the raised plastic portion?

I thought about getting out the hack saw, but didn't know for sure enough that that was the only problem. So I didn't want to do anything to hurt the body by forcing something to fit.

So, is this basically a $20 lens that I won't feel bad about tampering with?

Hmm, just saw the next post, I will try removing it tonight.
11-08-2011, 05:08 PM   #6
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The hack saw will do just fine! Get rid of the thing!

You can compare with a Pentax lens and see how little of the thing to leave (or just cut it all!).

Since it's plastic, perhaps all you need is a sharp knife.
11-08-2011, 05:42 PM   #7
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Don't even cut it. Just put it and the screws that held it in a plastic bag, and store them in case you want to sell the lens intact at some later point. It doesn't need that ring to function, and will work perfectly without it.
11-08-2011, 09:17 PM   #8
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If you can remove that black raised part without affecting anything else, do it. If you can't, take off the entire mount and grind that thing down. I used a drilling machine with a grinding bit and I eliminated a metal flange like that in 15min. Taking off the mount avoids damaging the rear element during this operation.

Vivitar for some reason added that piece to the mount. It worked fine on Pentax film cameras, but on digital ones it cannot be mounted because it hits the SDM contact.

11-09-2011, 06:28 AM   #9
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This post may help...with before and after flange surgery pics. Worked for me.
11-09-2011, 09:31 AM   #10
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Thanks everyone. I tried just removing the flange last night, but my tiny hobby screwdrivers were not tiny enough. I brought it to work today to see if the computer guys had tinier tools to borrow.

And thanks Erds for the heads up on that thread. Looks like I searched for the wrong thing. I thought it was a P/KA issue and not an obscure Vivitar mount issue.

I did look at my other lenses. The other Vivitar (PK, no "A" setting) has a short <1/2 inch flange like each of the modern Pentax and Tamrons. The 2 old Makinons had no flange at all. I know they fit and work so I'm sure that if I can just remove the flange it should be fine. I'd rather not get into mount-altering surgery since this lens's future is probably the auction block antway.

Thanks again for your advice.
11-09-2011, 12:41 PM   #11
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QuoteOriginally posted by wzdevito Quote
I'd rather not get into mount-altering surgery since this lens's future is probably the auction block antway.
As long as you do the surgery well, it can only increase the chance of you being able to sell the lens in the future - you don't want the buyer to ask for their money back because they cannot mount it.
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