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07-16-2010, 09:14 AM   #1
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Tamron Adaptall Mount Confusion

I've searched through a bunch of different postings and haven't seen (or recognized ) the answer to my question............

I'm confused about the way the Tamron Adaptall mount functions. I've seen Adaptall, Adaptall 2 and for Pentax, both Adaptall P/K and Adaptall P/KA (and the think Adaptall 2 for both P/K and P/KA).

What I'm mainly confused about is the "A" function - is that function in the Adaptall mount, or does the lens itself have to be an "A" lens?

07-16-2010, 09:24 AM - 1 Like   #2
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Adaptall-2 P/K = the lens acts like a K M lens, ie. you are on manual exposure with a dSLR
Adaptall-2 P/KA = the lens acts like a K A lens, ie. you can use the auto exposure modes with a dSLR
The lens itself is the same, the smallest stop is also the 'ae' stop. Thus whichever camera brand's mount is used, the lens sets the same way.

Here's an illustration to make it clearer, I hope:


You can see the red AE next to f/32 - with a K-M mount, that's just another f/stop. But with a K-A mount, it acts like a Pentax lens with an A setting.

Here's the K-A mount - there are contacts and tabs and so on - including a lock/release for the AE setting.




unfortunately I don't have a pic handy of the K-M mount to compare


Only Adaptall-2 lenses have this - though people often just say Adaptall to mean Adaptall-2.
07-16-2010, 09:58 AM - 1 Like   #3
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What Jussi said...

I have both adapters and will post a photo of the P/K if I get a chance. Be aware that there is also a Ricoh-P version. I think it is called P/KR. It has a ball-fitting version of the Ricoh pin and may have some risk of jamming onto the mount of Pentax AF bodies.

Edit:
Here is a photo of the P/K version. It differs from Jussi's P/KA above in the following points:
  • No electric contacts
  • No lock at the smallest aperture to support the "A" position
  • Presence of a second aperture scale on the mount ending at f/32. The purpose of the second scale is to support the "Judas Window" aperture display on cameras with that feature (e.g. Pentax LX, KX, and others).


K10D, Sigma 50/2.8 EX DG Macro


Steve

Last edited by stevebrot; 07-16-2010 at 10:56 AM.
07-16-2010, 10:00 AM   #4
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AD-2

Chip, another way to look at it is to realize the various adapters are designed to mate with the body functions and match the lens registry distance, not for the lenses themselves which are essentially identical in functioning.

It's less confusing if you associate the capability of the camera mount as identified on the adapter rather than the class of Tamron lens or whether it's an AD or AD-2 adapter.

On any lens you can mount an M42 adapter or a PK adapter which will act like Pentax K- and M-lenses without AE, or you can use a PK/A adapter which transfers aperture info to those bodies capable of reading it. Electrical contacts in the PK/A adapter use the f32/AE position to sense the f-stop data and a tab on the adapter acts as a Man/Auto switch similar to an SMC A type lens.

An interesting trick is that an Adaptall M42 adapter used with an M42/K lens adapter allows AV as well as Manual exposure functions just as a Pentax M42 lens would.

I've attached a scan of the English portion of the Adaptall-2 instructions which don't directly address your question but may be of interest.

H2

If you really want to confuse the issue, throw in the T-mounts!

Attached Images
File Type: pdf Adp-2 inst.pdf (413.5 KB, 669 views)
07-16-2010, 11:10 AM   #5
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QuoteOriginally posted by pacerr Quote
...An interesting trick is that an Adaptall M42 adapter used with an M42/K lens adapter allows AV as well as Manual exposure functions just as a Pentax M42 lens would...
...sort of...

As noted on another thread and elsewhere on this site, the Adaptall-2 M42 adapter lacks the A/M switch and will be limited to wide open use if adapted to K-mount with most M42-to-K adapters. It is possible to modify the Adaptall by gluing the pin in the actuated position, but I would suggest that it may be better to get the P/K version (the price is probably less) and chop off the aperture actuator lever. That will make the lens with that adapter fully manual and perfect for use in Av mode.


Steve


(To be honest, I would not cripple either mount...after all, they are no longer being made...)
07-16-2010, 12:46 PM - 1 Like   #6
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QuoteOriginally posted by stevebrot Quote
. . .sort of. . . As noted on another thread and elsewhere on this site, the Adaptall-2 M42 adapter lacks the A/M switch and will be limited to wide open use if adapted to K-mount with most M42-to-K adapters. It is possible to modify the Adaptall by gluing the pin in the actuated position,
True -- all considerations for lenses without an A/M switch pertain.

But if this is your chosen mode of operation it's economically feasible to permanently (or temporarily) modify an M42 adapter to force Manual mode.

Caution: you CAN'T fix the aperture pin/lever in the depressed position BEFORE mounting the adapter to the lens or the foot plate jams against the aperture lever in the lens. However it can be disassembled in the depressed condition -- observe the aperture lever pivot point in the lens.

As a work-around, I've used a P/ES AD-2 adapter with a rolled up piece of heavy rubber band inserted with tweezers to hold the pressure plate in the engaged condition after mounting the adapter for field expedient close-up tasks.

But frankly, the PK/A adapters aren't really that expensive considering the versatility and quality of the lenses and the price compared with 'modern' lenses.

H2
07-16-2010, 01:59 PM   #7
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I would insert one note of caution regarding the P/KA adapter. While many users on this forum have had no problems, I have found mine to be somewhat temperamental. The contacts often don't make a good connection. This can be remedied by fiddling with the lens on the mount a little when it happens, but it is still a pain. Improvements may be made by cleaning the contacts, but it is not fail-safe.

As a result, I seldom use my P/KA adapter and personally consider it a poor investment at the current price point. I would suggest that a person just getting into Adaptall-2 lenses consider purchasing the P/K adapter first and move up to the P/KA if they see a good deal or are frustrated with green button metering in M-mode.


Steve
07-16-2010, 02:24 PM   #8
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QuoteOriginally posted by stevebrot Quote
. . . somewhat temperamental. This can be remedied by fiddling with the lens on the mount a little . . .
Two of the four PK/A'S I use have that problem. The adapter latches about one degree of rotation beyond the proper registration point. Someday I'm gonna widen the latching notch a bit with a Dremel burr and re-bush it with epoxy it so it seats properly.

Someday . . . yeah, right after I get around to putting labels on 'em so I know in advance when I'm about to pick up a fussy one.

Hey, Chip. What was your question again?

H2

07-16-2010, 03:14 PM   #9
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QuoteOriginally posted by stevebrot Quote
I would insert one note of caution regarding the P/KA adapter. While many users on this forum have had no problems, I have found mine to be somewhat temperamental. The contacts often don't make a good connection. This can be remedied by fiddling with the lens on the mount a little when it happens, but it is still a pain. Improvements may be made by cleaning the contacts, but it is not fail-safe.

As a result, I seldom use my P/KA adapter and personally consider it a poor investment at the current price point. I would suggest that a person just getting into Adaptall-2 lenses consider purchasing the P/K adapter first and move up to the P/KA if they see a good deal or are frustrated with green button metering in M-mode.


Steve
Hi Steve,

Have you seen this article?

https://www.pentaxforums.com/forums/pentax-lens-articles/50689-fixing-tamron-...a-adapter.html

I learned about this trick years ago, and have needed the fix on all but one of my PK/A adapters. The article explains the cure pretty simply.

Scott
07-16-2010, 03:49 PM - 1 Like   #10
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Some of this has been covered but a few additional points.

There was a p/k mount that was released with the original Adaptall lenses that if functionally the same as the P/K. It just looks different because of different machining style and labeling. However, they are relatively rare compared to the newer version of the P/K. The P/KA came out after the ad-2 series was in production to give the the same capabilities of the Pentax A series. There is also a PK/R for Ricoh that has the damn Ricoh pin.

In addition to the Pentax m42 mount for the regular bodies, there was the one with the gear for the Electro, ES, ES II and Spot F open aperture bodies. There was also a couple of m42 variations for some other body Brands as well.
07-16-2010, 03:51 PM   #11
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Now lets talk about Adapt-A-Matic mounts. Just kidding.
07-16-2010, 04:08 PM   #12
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Great help - THANKS!!

Jussi, Steve, H2, Scott, Blue - thanks all for the great info. Really appreciate it - clears up a long-standing point of confusion!!
07-16-2010, 08:57 PM   #13
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QuoteOriginally posted by snostorm Quote
Hi Steve,

Have you seen this article?

https://www.pentaxforums.com/forums/pentax-lens-articles/50689-fixing-tamron-...a-adapter.html

I learned about this trick years ago, and have needed the fix on all but one of my PK/A adapters. The article explains the cure pretty simply.

Scott
Yep, I read it when it was first posted and gave the fix a try. I don't know that it improved anything however. I still get the intermittent F---.


Steve
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