[roy]

i've got one of these but it doesn't work as a PKA mount.. it does well as a PK mount but will not transmit aperture value to the camera.. anybody else had this problem?? know a fix??
i've also got a short tamron zoom that only works with a PKA adapter from f8 and above..

[ryan s]

Yep! These things are a PITA.

One thing to check is that the lens is locking in the AE position. The little black button on the side of the mount might need a workout. Remove it from the lens, and just work all the locks/buttons, slide the aperture coupling, and flip the aperture lever a few times.

One of my PKAs locks, the other one doesn't except on one lens.

[roy]

Yep! These things are a PITA.

One thing to check is that the lens is locking in the AE position. The little black button on the side of the mount might need a workout. Remove it from the lens, and just work all the locks/buttons, slide the aperture coupling, and flip the aperture lever a few times.

One of my PKAs locks, the other one doesn't except on one lens.

both of mine lock and will go into the AE setting. it's just on of them has no AE.. what's weird is that even the cam will not display the ap value you can rotate the wheel like always and the cam will stop down. when you ck the image it does show the different f-stops..

[Lowell Goudge]

I find the operation of my PK-A a little inconsistent, where I believe there is a contact problem specifically with the pin that tells the camera the lens is in the A setting. I find that a slight twist of the lens on the camera mount corrects this. I have not explored yet whether it is an internal contract problem, or a simple matter of the contact on the lens being dirty.

I have also tried other PKA mounts and tamron lenses, and found some problems with the "clips" on the mount remaining engaged into the slots on the lenses.

The other thing I have found, at least wioth the ones I have tested so far, is the inability to get an apature faster than F4 with the lens in AE mode. I read somewhere this was the case but I can't find the link now,

[ryan s]

That's strange the lens has no AE setting...all 3 of mine do. Also strange that the cam doesn't just blink F-- when the aperture ring is unlocked.

The f/4 issue has been discussed before, and some have said it's "rubbish" that the lens can't go below that number. It is true though. I'm looking at my cam right now, at f/4, with my f/2.5 lens on it. I sold all my other cams, otherwise I would take a pic to show it.

Just tried the other one...it locks, but just shows F--.

I've only gotten f/2.5 to work once...once...

[roy]

here's an answer that worked, from scott at steve's.. i used a fingernail file to rough up the area in question..

The problem is usually due to a bad ground in the PK/A adapter. just to the left of the last contact pin, you'll see the end of a screw coming into the adapter base from the other side. The theory is that Tamron used a thread sealer to lock this screw in position, and the excess was wiped off, but a very thin residue remains, and this thin film insulates the area preventing a ground here with a pin on the camera body. try scraping about a 1/4" area around the screw end with a knife blade. Clean away the scrapings and blow off the end of the lens and try it on the camera. If you still have no aperture show up, in the VF, enlarge the area a little at a time until you get a solid contact (try not to scrape too deep, you don't want to make a dip in the metal). I've had some that required clearing as much as @ 3/8" to make the right contact.

thank you scott!!

[Matjazz]

The other thing I have found, at least wioth the ones I have tested so far, is the inability to get an apature faster than F4 with the lens in AE mode. I read somewhere this was the case but I can't find the link now,

I might have the problem that might be described like that only the trouble is somewhere else. When using pka adapter in A mode there is only slight difference in exposure if I set aperture to 2.8 or 4 (at same shutter speed) but if i set aperture on lens the difference is there. The conclusion is that aperture is actually one stop bigger than displayed in camera when in A mode meaning f4 is actually f2.8 and f5.6 is actually f4 ... I confirmed this using another lens with same focal length. It does have one good side. When I use it with 1.4x TC the aperture in camera is right.

[ryan s]

Roy, which left? With the contact pin at 12:00 or 6:00 when looking at the back of the lens? I'm assuming 6:00 since I do see a little glue-like substance on a screw head. Let me try it on both, and I'll post back.

[ryan s]

Hmm well...ok...that did the trick on one (goes to f/2.3), but the other one has locking issues. It still gives me f/4 and goes to F--when moved out of the AE setting.

Doesn't matter too much since I have a couple lenses that are f/4...

Thanks for the tip

[roy]

looking at the pins with them at 6oclock position.i roughed up everything from the middle pin and to the left for about 1/2''.
this also fixed a problem on a 80-210 that would only work at f8 and above. now it goes all the way to f4

[Ben_Edict]

The other thing I have found, at least wioth the ones I have tested so far, is the inability to get an apature faster than F4 with the lens in AE mode. I read somewhere this was the case but I can't find the link now,

This is no general rule. My Tamron 300 2.8 easily opens up to 2.8 and the camera display is correct on my K10 and K20. So, if a lens doesn't open fully, it is either one of the over-sensible Adapt-all adapters or may be a very old lens?

Ben

[jonny1986]

i have found a tamron 300 2,8 adaptall , the gray, at 630 euro in a shop. what do u think of the price?
the manual version the a 300 2,8 cos 1200 euro on ebay, and the fa at more than 2000.

[Class A]

The theory is that Tamron used a thread sealer to lock this screw in position, and the excess was wiped off, but a very thin residue remains, and this thin film insulates the area preventing a ground here with a pin on the camera body.

That worked for me too (I originally found the solution at DPR). I created a "Fixing Tamron Adaptall P/KA Adapter" article which comes with a corresponding image of the mount.

The conclusion is that aperture is actually one stop bigger than displayed in camera when in A mode meaning f4 is actually f2.8 and f5.6 is actually f4

Is the adapter communicating the correct minimum aperture to the camera? If not, that could be the reason. You could check this explanation of the KA mount to see which pins should be shorted to the ground for a particular lens on the adapter.

[Blue]

i have found a tamron 300 2,8 adaptall , the gray, at 630 euro in a shop. what do u think of the price?
the manual version the a 300 2,8 cos 1200 euro on ebay, and the fa at more than 2000.

That is not a bad price but not particularly good either. That is extrapolating that to prices in the U.S. It is also assuming the lens is in good shape. If it were the 360B, I'd say the price is good. The gray one is the 60B.