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04-27-2012, 09:35 PM   #1
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Adaptall K - KA conversion

Some old posts mention this conversion but my search turns up nothing about how to do it. Anybody know?

Thanks,

Paul

04-27-2012, 10:23 PM   #2
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It's simple. Trade in your PK adapter for a PK/A.

There's no practicable or economical way to do a PK to a true PK/A adapter conversion as a one-off, DIY exercise.

H2
04-27-2012, 11:26 PM   #3
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Agreed

QuoteOriginally posted by pacerr Quote
It's simple. Trade in your PK adapter for a PK/A.

There's no practicable or economical way to do a PK to a true PK/A adapter conversion as a one-off, DIY exercise.

H2
Bonjour,

I would suggest getting a PK/A ... worth a reasonable expenditure in the long term if you use a lot the AD-2's ... like me. Although I got my 2 PK/A for a very reasonable cost each time ... which is why I have one extra as a "backup".

Salut, John le Frog
05-01-2012, 10:23 PM   #4
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QuoteOriginally posted by pacerr Quote
There's no practicable or economical way to do a PK to a true PK/A adapter conversion as a one-off, DIY exercise.
Period...end of discussion! I own both adapters and the linkage for the PK/A is a non-trivial piece of engineering. If your camera is a recent Pentax dSLR, shoot with the PK in M mode and green button and be happy.


Steve

(...actually prefers his PK over the PK/A)

05-02-2012, 06:47 AM   #5
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Thank you for superior wisdom,and I will now be content.

Blessings,

Paul
05-02-2012, 06:49 AM   #6
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QuoteOriginally posted by stevebrot Quote
Period...end of discussion! I own both adapters and the linkage for the PK/A is a non-trivial piece of engineering. If your camera is a recent Pentax dSLR, shoot with the PK in M mode and green button and be happy.
Or find a P/U adapter (m42) and that way you can use Av mode too.
05-02-2012, 07:02 AM   #7
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QuoteOriginally posted by pacerr Quote
It's simple. Trade in your PK adapter for a PK/A.

There's no practicable or economical way to do a PK to a true PK/A adapter conversion as a one-off, DIY exercise.

H2
QuoteOriginally posted by stevebrot Quote
Period...end of discussion! I own both adapters and the linkage for the PK/A is a non-trivial piece of engineering. If your camera is a recent Pentax dSLR, shoot with the PK in M mode and green button and be happy.


Steve

(...actually prefers his PK over the PK/A)
Actually, I am not so sure.

I think it all comes down to whether the adaptall II PK aperture lever motion is the same as the PKA lever motion.

If it is, then the modification, while not a true PKA mod, but a lens specific PKA mod is rather simple.

It is the same mod as any K to KA lens. What you need is, one spring loaded pin (the ones used in grid array IC mounts work, and are self contained, or one stolen from any PKA lens that is scrap) located correctly at the third pin location away from the lens locking pin (this may be tricky, i use a body mount from an old scrap cheap pka 2x TC as a drill template) , and then to correctly drill the insulating areas to match the minimum and maximum aperture for the lens in question.

This really only requires some patience and a little machine shop (drill press and soldering) skills.

I have not tried it as I only have one PK adapter and am keeping it intact (I have 2 PKA and 1 M42 adapter as well, but these reside on my 3 adaptall lenses)
05-02-2012, 07:41 AM   #8
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QuoteOriginally posted by Lowell Goudge Quote
I think it all comes down to whether the adaptall II PK aperture lever motion is the same as the PKA lever motion.
It isn't...

The P/K adapter is a fairly simple lever while the PK/A has a roller acting against a cam.


Steve

05-02-2012, 07:48 AM   #9
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QuoteOriginally posted by stevebrot Quote
It isn't...

The P/K adapter is a fairly simple lever while the PK/A has a roller acting against a cam.


Steve
Thanks, I was not sure, and that is the limiting factor.

The lever will result in an aperture movement like a K lens, with diameter linear with movement, not area, any attempt to put the aperture coding into the lens will result ininconsistent exposure through the range, as I documented in a Rikenon 50mmF2 conversion from PK to PKA
06-01-2012, 03:51 PM   #10
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Lucky I guess

I bought a bunch of bags of Pentax MF and AF film camera gear and ended up with a PK for every Adaptall lens and 2 PKA's for my 2 favorite Tamrons. First one is on a 24mm and the other on my 70-210. At that time 3+ years ago I just never thought about a scarcity of the adapters. I just use the M mode with the plain PK's and am quite happy with the results. Of course I am just an advanced snap shot shooter that occasionally gets a real high quality image which accounts for my contentment. Almost 1/3 of my lenses are screw mount and I get a lot of better results from them than some of the AF lenses. When I was using film I collected a number of rare manual lenses for the old Canon FD mount. Then changed to Pentax because all my longer prime lenses and some of the short ones were screw of T mount types and were inexpensive to adapt to the digital body. Then I sold a large group of my old lenses to another collector for too low a price. Just was too lazy to eBay them. Now I know how to make an FD into a manual on a Pentax body and boy do I regret that sale!!!
06-01-2012, 04:22 PM   #11
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I wouldn't have guessed there is an easy conversion of FD to PK; a bit curious cuz I still have some FD stuff. I am boiling down my AD2 set and it is looking real good; hoping to round it out with a 51A. We have more fun than sane people, don't you think?

~Paul
06-01-2012, 06:13 PM   #12
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QuoteOriginally posted by Melismus Quote
I wouldn't have guessed there is an easy conversion of FD to PK; a bit curious cuz I still have some FD stuff. I am boiling down my AD2 set and it is looking real good; hoping to round it out with a 51A. We have more fun than sane people, don't you think?

~Paul
The conversion info is in the Impossible Lens Club thread. It is possible due to the thickness of the FD mount. It's easier with the breech mount units and the Fl lenses due to the increased complexity of the aperture on the nFD mounts. Since you take so much length off the back of the lens without disturbing the aperture mechanism you get into the range from the rear element so that it is just right from the focal plane then all one has to do is insert a screw into the former location of the aperture release pin and mount up a flanged K mount from M42 adapter and you get a manual lens out of it. This is especially useful for the "L" series lenses that are orphaned now and some of the regular ones that were outstanding. If you own a few cheap FD lens you could practice on one of them. I think I know of 5 or 6 300mm f2.8 conversions by now. Plus I think someone did a 400 or 500 or both. Personally I regret the day I did not buy a Canon "L" series 200mm f1.8 FD mount about 3 years ago. Went for around $100 on eBay which is a steal. Now they are back up around a thousand but the others are considerably less expensive.

Last edited by kacansas03; 06-01-2012 at 06:15 PM. Reason: omission
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