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12-05-2011, 11:01 PM   #1
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Auto aperture on Tamron lens

I've just aquired a new in box Tamron 70-210 Macro.
To go with it I also got a new a nearly new P/Ka adaptall mount.

Everything fits together nice and firmly, I cleaned all the contacts set it to 'A' on the aperture ring and went out to play.
I'm getting nice photo's with exposure seemingly ok but I'm not seeing any aperture setting in the viewfinder.

Any suggestions to help me out.

Thanks.


Last edited by Mychael; 12-05-2011 at 11:23 PM.
12-05-2011, 11:07 PM   #2
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Are you getting F--?

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12-05-2011, 11:12 PM   #3
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QuoteOriginally posted by Adam Quote
Are you getting F--?
Yes I am Adam.
I suppose I should re-check my camera settings but I know I have had it set to 'allow'/permitted for aperture ring.
12-05-2011, 11:22 PM   #4
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Ok, you can all stand down. For reasons known only to itself the camera and lens have decided they will take to each other. The aperture setting just suddenly popped up in the viewfinder and can be adjusted. Go figure.

12-06-2011, 12:51 AM   #5
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It is not uncommon that the KA adaptall mounts require a bit extra pressure to get into position than an ordinary KA mount. One of my KA adaptall mounts do this, the other not. Not sure why.
12-06-2011, 12:56 AM   #6
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Bummer huh, now I'm not game to take it off in case I upset it again.
12-06-2011, 01:48 AM   #7
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QuoteOriginally posted by Mychael Quote
Bummer huh, now I'm not game to take it off in case I upset it again.
Well, as you said: You get nice pictures even though the display shows "F--" so don't be too afraid. It's a problem we all encounter with Adaptal-2 P/KA Custom Mounts now and then.

And the remedy is usually to GENTLY twist the lens forth and back a few times. You may find a similar discussion here, where Northern Soul encountered the same problem to a more extreme degree:

https://www.pentaxforums.com/forums/lens-clubs/59769-adaptall-mount-club-tamr...ml#post1713663
12-06-2011, 02:15 AM   #8
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I'm not sure if the problem is between the mount and the camera or between the adaptall mount and the "raw" lens mount. But I've heard of similar behavior for Nikon and Olympus adaptall mounts (on film bodies), so that would suggest that the later case. Anyway, the cure is like Stone G describes it. Make it a habit every time you change to an adaptall lens. It is disturbing, but not enough to keep me away from the many fun adaptall lenses.

12-06-2011, 06:53 AM   #9
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my KA mount on the 200-500F5.6 does the same thing, it is I suspect part camera and part adaptor. I seem to think it is getting better over time, maybe I just know and accept it now, maybe it had a dirty spot that is cleaned off, who knows???
12-06-2011, 12:51 PM   #10
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You need to thoroughly clean the PK/A mount of accumulated debris from 20+ years of mounting and dismounting from the Adaptall lenses. Easiest way to do this is to drown the mount with naptha while working the moving parts (the two indexing levers), blot the solvent with paper towel and repeat the process until the blotting shows little or no grime coming from the PK/A mount. I have had four PK/A mounts that were troublesome and not reporting maximum aperture larger than f4.0, after cleaning them as described, three work perfectly and report maximum aperture to f2.5 (2.4 on camera). The remaining one work perfectly except the reported maximum aperture still shows f4.0 no matter what lens it's mounted on. Solution: keep it mounted on the SP 54B, 300/5.6 lens.
12-06-2011, 02:02 PM   #11
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QuoteOriginally posted by excanonfd Quote
You need to thoroughly clean the PK/A mount of accumulated debris from 20+ years of mounting and dismounting from the Adaptall lenses. Easiest way to do this is to drown the mount with naptha while working the moving parts (the two indexing levers), blot the solvent with paper towel and repeat the process until the blotting shows little or no grime coming from the PK/A mount. I have had four PK/A mounts that were troublesome and not reporting maximum aperture larger than f4.0, after cleaning them as described, three work perfectly and report maximum aperture to f2.5 (2.4 on camera). The remaining one work perfectly except the reported maximum aperture still shows f4.0 no matter what lens it's mounted on. Solution: keep it mounted on the SP 54B, 300/5.6 lens.
mounts that always show F4 have lost contact to the aperture pins and the lens base. I had one like this that I added a small bridge to short the two parts of the mount out. I think this comes from picking up a lens that is too big and heavy with the camera, as the PKA mount is somewhat fragile, compared to the PK.

I would hate to think how much one would bend on my 200-500/5.6 if i picked up the 2.7KG of lens with the camera
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