Do you have a problem with a Tamron Adaptall PK/A adapter whose "A" functionality is not available or only if you do not completely mount the adapter to the camera, i.e., twist it back a little after mounting?

Chances are that it does not index on the body too far clockwise and that you can fix it within a minute.

The culprit may be one of the three screws which are fixed using a glue that electrically insulates them from the camera mount. If this is the cause of your problem then removing the glue from the end of the screw which is closest to the other electrical contacts (i.e., the top rightmost in the image below), e.g., with the tip of a knife, will make establish contact to the body mount again. This made my adapter work and I'm indebted to marvintm whose post "Re: How to fix bad Tamron KA mount" provided me with the solution.

However, since the illustrating images from his post are no longer available, I initially had trouble finding the screws. I finally found them and below is an image showing the location of the screw ends.

Contrary to marvintm's description, the glue on my screw end was not easily discernible by a light blue/green colour. I just lightly scratched on the screw end just in case and the adapter now works like a charm.

Good luck!

P.S.: This explanation of the KA-mount contains all the information required to know for which lens (minimum and maximum f-ratio) the pins should be shorted to the ground by the adapter. This should help troubleshooting if the camera doesn't use the correct aperture range. Note that the adapter does not fully support lenses with a minimum f-ratio slower than f/4 if the maximum f-ratio is f/22 and there is an "AE" setting or f/32 and there is no "AE" setting. Alternative explanations of contacts are Mark Roberts matrix metering mods page and this detailed explanation of the adapter contacts.

P.P.S.: You may want to try to convert a P/K adapter to one that supports P/KA functionality for a specific lens.

[Class A]

Perhaps your adapter was damaged when someone did not obey the instructions (that are often not included).

IIRC, the lens has to be set to wide open before attaching it to the adapter. Not adhering to this prerequisite can bend internal parts in the adapter.

[fsdogwood]

Is the lens wide open when it's mounted on the camera (as it should be), or is it closed down to the minimum aperture opening?

It's closed, even if put on camera and move the e-dial, the display could be 2.8, 4, but the aperture stays closed

---------- Post added 09-12-2015 at 09:09 PM ----------

And is it actually in the 'AE' position? (You must use little black button on mount to get it in there.)

Yes, it is in AE position.

These are the steps I use:
1. set the lens to its widest aperture (2.8)
2. push the adapter on, when snugly start turning it, until the latch clicks in then spring out to its original position
3. set the 2 tabs to the slots (if they are not there yet)
4. set the lens to f22, push the AE-lock tab, now set to f32/AE, the lens is closed down (only a small hole formed by the aperture ring)
5. put the lens on camera
6. turn on the camera in Av mode, set the focal length,
------> the LCD may display as f2.8, or f4
------> but the VF is dark, all the time (while the lens in 'AE' mode) that it's hard to focus
------> and the aperture stays closed

Thanks for all the replies, maybe I'll bend the aperture limiting tabs in a little bit? Should the inner white part touch the lens wall? It might be possible a bad adapter, but I am trying to identify.

I guess my questions are:
1. when you set the lens to 'AE' mode, does the lens go wide open or stay closed?
2. when you put the lens on camera, turn on camera in Av mode, is the lens wide open or closed?
....
3. I can imagine that one can turn the e-dial, to, say f8, and the lens is still open, correct?

[vonBaloney]

It's closed, even if put on camera and move the e-dial, the display could be 2.8, 4, but the aperture stays closed

---------- Post added 09-12-2015 at 09:09 PM ----------



Yes, it is in AE position.

These are the steps I use:
1. set the lens to its widest aperture (2.8)
2. push the adapter on, when snugly start turning it, until the latch clicks in then spring out to its original position
3. set the 2 tabs to the slots (if they are not there yet)
4. set the lens to f22, push the AE-lock tab, now set to f32/AE
5. put the lens on camera
6. turn on the camera in Av mode, set the focal length,
------> the LCD may display as f2.8, or f4
------> but the VF is dark
------> and the aperture stays closed

Thanks for all the replies, maybe I'll bend the aperture limiting tabs in a little bit? Should the inner white part touch the lens wall? It might be possible a bad adapter, but I am trying to identify

Well, you understand when you turn the dial, nothing is supposed to happen -- that's setting the aperture for the shot but not actually stopping yet. But unless you're using the optical preview or actually tripping the shutter to take an image, the lens should stay wide-open at all times. (Just like any other lens with an 'A' setting or any more modern autofocus lens with no aperture ring.) So it does sound like you have a problem, but moving the dial is not supposed to cause any mechanical reaction...

[fsdogwood]

Well, you understand when you turn the dial, nothing is supposed to happen -- that's setting the aperture for the shot but not actually stopping yet. But unless you're using the optical preview or actually tripping the shutter to take an image, the lens should stay wide-open at all times. (Just like any other lens with an 'A' setting or any more modern autofocus lens with no aperture ring.) So it does sound like you have a problem, but moving the dial is not supposed to cause any mechanical reaction...

The problem is, the lens stay all the way closed all the time. The VF is very, very, very dark, just cannot focus.
If I move off the 'AE' position, I can do the "stop down" by turning the aperture ring to, say, f4 and I now can focus.

If the lens should stay wide open unless doing a preview or actually trigger the shutter, could you mind let me know when the lens becomes open? as soon as put on the camera or after the camera turned on?

---

Last edited by fsdogwood; 09-12-2015 at 06:52 PM.

[vonBaloney]

The problem is, the lens stay all the way closed all the time. The VF is very, very, very dark, just cannot focus.
If I move off the 'AE' position, I can do the "stop down" by turning the aperture ring to, say, f4 and I now can focus.

If the lens should stay wide open unless doing a preview or actually trigger the shutter, could you mind let me know when the lens becomes open? as soon as put on the camera or after the camera turned on?

As soon as you mount it, except for the (mirrorless) K-01, which waits until you turn it on. Every K mount lens should be wide-open as soon as you mount it and stay that way until you shoot. (Even fully manual lenses with no 'A'). So this one should be wide-open even if you don't put it in AE. Whether it is the lens or the Adaptall mount to blame I can't say unless you have another mount to try.

Now if it is unmounted off the camera, then the aperture should go to where ever the ring is set, and the lever should open it and then snap closed again if you release it...

[excanonfd]

When you have the lens dismounted from the camera and AE lock engaged, the lens diaphragm should be closed. If you move the aperture actuating lever on the lens, it should open and close the diaphragm, does your lens do that? Does the actuating lever spring back to the original position when let go?

The gap between the actuating lever and the actuating lever shield should be about 2mm, you may need to bend the lever to conform to that spec.

[fsdogwood]

When you have the lens dismounted from the camera and AE lock engaged, the lens diaphragm should be closed. If you move the aperture actuating lever on the lens, it should open and close the diaphragm, does your lens do that? Does the actuating lever spring back to the original position when let go?

The gap between the actuating lever and the actuating lever shield should be about 2mm, you may need to bend the lever to conform to that spec.

When the adapter is put on the lens, and AE lock engaged, the lens diaphragm is closed.
Move the level from the back of the adapter, the aperture would open, and when the level let go, the aperture will be closed.

I'll have to study the lever and its shield to figure out the gap thingy.

Re-read the k-mount page, try to understand the following: "The lens aperture ring has an additional setting that is marked with an "A". It is always the left-most aperture setting, and therefore functions as the lens' narrowest f-stop. Because of this, when the "A" setting is engaged, the lens internal mechanics pull the diaphragm blades towards their "as closed as possible" position. On the other hand, when the lens is mounted on a camera body, the diaphragm release counteracts the lens mechanics, and keeps the diaphragm fully open."

Appreciated

---

Last edited by fsdogwood; 09-13-2015 at 03:20 AM.

[marcusBMG]

One of my PKA adapters was playing up - I was taking some comparison pics between my 01B and 13A and the lens wasn't stopping down. Fortunately I had a second mount with me.
Back at home I inspected things to see what might be the problem. Electrically the mount seemed fine - registering correct f numbers and responding to the camera. I figured out that the movement of the aperture lever was sticky.

Pic 4 below shows the mount with the cover off (4 small screws around the edge of the bayonet). R is the roller that the aperture lever moves against. E is the electrical contact that codes the f-stop. I suspect that it is an issue with this that causes some mounts to only show f4. P is the plate that pushes against the aperture lever on the lens. S are the screws to completely disassemble (E needs to be removed first - take care not to bend the contacts).
It wasn't easy to see but finally I realised that the arm was catching on the roller R bracket. You can see the shiny wear spot on the corner of it in pic 1 below.

A minute with a jewellers file, then reassembly, fixed things!
(pics snapped with ever reliable smc-a 50mm, fill flash pics 1 and 2).

[Skodadriver]

Do you have a problem with a Tamron Adaptall PK/A adapter whose "A" functionality is not available or only if you do not completely mount the adapter to the camera, i.e., twist it back a little after mounting?

Chances are that it does not index on the body too far clockwise and that you can fix it within a minute.

The culprit may be one of the three screws which are fixed using a glue that electrically insulates them from the camera mount. If this is the cause of your problem then removing the glue from the end of the screw which is closest to the other electrical contacts (i.e., the top rightmost in the image below), e.g., with the tip of a knife, will make establish contact to the body mount again. This made my adapter work and I'm indebted to marvintm whose post "Re: How to fix bad Tamron KA mount" provided me with the solution.

However, since the illustrating images from his post are no longer available, I initially had trouble finding the screws. I finally found them and below is an image showing the location of the screw ends.

Contrary to marvintm's description, the glue on my screw end was not easily discernible by a light blue/green colour. I just lightly scratched on the screw end just in case and the adapter now works like a charm.

Good luck!

P.S.: This explanation of the KA-mount contains all the information required to know for which lens (minimum and maximum f-ratio) the pins should be shorted to the ground by the adapter. This should help troubleshooting if the camera doesn't use the correct aperture range. Note that the adapter does not fully support lenses with a minimum f-ratio slower than f/4 if the maximum f-ratio is f/22 and there is an "AE" setting or f/32 and there is no "AE" setting. Alternative explanations of contacts are Mark Roberts matrix metering mods page and this detailed explanation of the adapter contacts.

P.P.S.: You may want to try to convert a P/K adapter to one that supports P/KA functionality for a specific lens.

Many thanks to the author(s) of the article on the Tamron P/KA mount fix. Having bought my 2nd P/KA mount ((my 1st worked immediately, was attached to a 28mm f2.8 (CW28) that the seller did not seem to realise featured this mount so it was cheap.)) I found the F stop was not displayed on my K5. Remembering having read on the Forum about a fix (or fixes) I re-read the articles, scraped the screw head and voila! It now transmits the aperture. This, plus the forum article on what to do with black anodised (or painted) lens mounts that would not stop down on the green button, have been godsends to a "greybeard" singularly lacking in most of the mental processes associated with the word "greybeard".

[stevebrot]

IIRC, the lens has to be set to wide open before attaching it to the adapter. Not adhering to this prerequisite can bend internal parts in the adapter.

The behavior is a little more complicated. Yes, the manual says to set the aperture ring to wide open. This is true for all Adaptall-2 mounts, not just the PKA. Doing so makes some difference on mount and may be required for a clean dismount. Here are a few bullet points:

For the PK and PKA (off the "A" position)

• If the aperture ring is set to full open, the adapter should cleanly dismount
• If the aperture ring is free to rotate (no ham fingers or palm in the way) and is set to narrower than about f/4, the ring will rotate to near f/4 as part of dismount and will dismount cleanly
• If the aperture ring is set to narrower than about f/4.0 and the ring is not free to rotate (typically due to how the lens is being held), the dismount will stop partway. Forcing it may damage the adapter.
• On mount, it makes no difference where the aperture ring is set except that it is more likely that both index tabs will be near their indents

For PKA in in "A" position

• As in the case above, the lens will dismount just fine as long as the aperture ring is free to rotate
• The caution is that doing so leaves the adapter in a strange state with one of the two index tabs locked in place
• An adapter in this state will mount up just fine, but the locked index tab will not seat into its indent until the aperture ring is moved to the "AE" position. Strangely, the adapter functions just fine as a "non-A" lens when in this state.
• I don't consider any of the above points to be good things

What to do?
I am a real fan of following instructions. Sooo...

• Make it a practice to set the lens full open before removing the adapter
• Never force the mount or dismount
• If you forget to set the aperture full open and there is a problem on dismount, let the aperture ring move free or reverse the operation and start again the right way

Steve

P.S. I don't have time to fiddle with adapters for other mounts, but I suspect the behavior is similar.

[fsdogwood]

When you have the lens dismounted from the camera and AE lock engaged, the lens diaphragm should be closed. If you move the aperture actuating lever on the lens, it should open and close the diaphragm, does your lens do that? Does the actuating lever spring back to the original position when let go?

The gap between the actuating lever and the actuating lever shield should be about 2mm, you may need to bend the lever to conform to that spec.

Thanks, bending the lever seems to have fixed the problem, now I got the lens working in A mode.
Regards

[photolady95]

Help! I just bought a PK/A adapter on Ebay. Seller states it is fully functional but after making sure I followed exact instructions, reading here about scratching the screw heads, camera still shows no f stop....only F____ So what else am I doing wrong?

On the instructions I got it shows a small black button(coupling ring) that the instructions say move this coupling ring in to the matching slot of the lens aperture ring.....but it doesn't move.

I still have the PK adapter. If I can't get this to work, it will be returned.

[pepperberry farm]

Help! I just bought a PK/A adapter on Ebay. Seller states it is fully functional but after making sure I followed exact instructions, reading here about scratching the screw heads, camera still shows no f stop....only F____ So what else am I doing wrong?

On the instructions I got it shows a small black button(coupling ring) that the instructions say move this coupling ring in to the matching slot of the lens aperture ring.....but it doesn't move.

I still have the PK adapter. If I can't get this to work, it will be returned.

Adaptall-2, right?

this has helped me tremendously:

Tamron Adaptall-2 Custom Mount for Pentax A

edit:

here is the .pdf of the actual owner's manual for the adapter, also....

http://www.gyes.eu/documents/adaptall-2_custom-mount_for-pka_manual.pdf

[photolady95]

Adaptall-2, right?

Yes. It's for the Tamron SP 90mm Adaptall-2 72B lens.

I already read the first link. Didn't help.

The .pdf is here in front of me, in paper form. Which still didn't help.
When I got the adapter today, it was in the original box with the instructions.

This is the lens I have:

https://www.pentaxforums.com/userreviews/tamron-sp-mf-90mm-f2-8-macro-1-1-72b.html

And on the Adaptall mount club, here, they told me I couldn't change the mount to have it function as an A lens.

Need to know why the coupling ring won't move to the aperture setting.

[marcusBMG]

Try pressing the little black auto aperture button while trying to move the black tab and see if it frees up. UPDATE stevebrot above in post #40 is more specific.

see the pic on my page:

Information page on Tamron adaptall, adaptall-2 system and lenses

This is normally the cause. Otherwise it may be that the mount has eg got damp in the past and seized up. I had one like that, I succeeded in in disassembling and lubricating it and it then worked OK.
What lens you have is irrelevant, the pka mounts work the same on all the adaptall lenses (except 06A). The only differences are sometimes the start f number doesn't quite match the lens eg shows f2.4 with the f2.5 lenses, f4 with the f3.8 lenses, f4 with the f5.6 lenses.
The mount won't communicate properly with the camera and show the f numbers if the tabs aren't properly aligned and seated.