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Old Sep 27, 2010, 11:32 AM   #1
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Default help with adaptall tamron 300mm 2.8 and IST aperture stuck on 2.8 or AE

my K20 is getting serviced, so I tested my new tamron 300 sp on my IST and the adaptall mount, soon as its mounted to camera switches the aperture to wide open (as if it wants camera to adjust aperture internally)

but obviously the ist reads it as F-- so, camera is pretty much stuck on 2.8 the entire time

obviously this isnt normal,

If i put my ist on part way (screw lenspartially on mount, but dont let it click, the flange on the adaptall mount doesnt lock in all the way, allowing me to use the camera as its supposed to)

but I cant be using my camera loosely screwed on, and I dont really want to file the flange on the adaptall mount down, as I think that would make it useable, Im not sure I want to make any alterations without first getting expert advice.

I tested on my friends IST DL and same problem occured.

can anyone help me? Its like the adaptall mount is forcing the lens to be on AE mode, no matter aperture setting.

lens aperture works 100% just fine when not attached to camera, and up until that last 'click' on the mount, locking it on


please help! Im trying to use the lens tomorrow in the mountains, but dont want to take it if im stuck with 2.8 the entire time


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Old Sep 27, 2010, 1:01 PM   #2
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Hi NMR,

There is a set procedure to mount the adapter to the lens. First rotate the lens aperture ring to max aperture (in this case f2.8), then mount the adapter to the lens by matching the green dots then rotating the adapter to the right until it locks. Once it locks, then rotate the aperture ring all the way to the AE setting and check that the two tabs on the adapter match the notches in the aperture ring. The adapter should be mounted correctly at this point. My experience is that on some lenses/adapter combos, the aperture ring will lock on the AE setting, and on others it doesn't lock, but these still work OK.

There's a possibility that some adapters might not allow one of the pins on the body to ground properly on the Adaptall mount, and you continue to get f---in the viewfinder unless you rotate the lens back a bit from being fully locked to the body. If yours does this, there's an easy fix. Post back in this thread if yours does this.

Sorry if I'm telling you stuff you already know -- most Adaptall problems come from new users, so I'm assuming. . .

Scott
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Old Sep 27, 2010, 1:56 PM   #3
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ahh. My first adaptall. Lens
I was hoping it was operator error. At work so can't test till tonight but do appreciate the tip
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Old Sep 27, 2010, 2:07 PM   #4
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Oh do I mount adaptall to camera first then attach lens or attach lens to adapter then adapt to camera
??

Last edited by NMRecording; Sep 27, 2010 at 2:19 PM.
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Old Sep 27, 2010, 2:17 PM   #5
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Sorry to keep bugging u. But would improper mounting cause it to keep reading f-- ? Because I am experiencing that unless I rotate adapter off came mount like u mentioned. Only asking because I ant get to really mount til ten pm n u might not get to me by tomorrow if issue is still there. So if the problem isn't. Due to me incorrectly mounting it then can u post fix so I know how to fix tonight before I head out at dawn Tomorrow? Sorry to b a pain. Hopefully my request makes sense
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Old Sep 27, 2010, 9:58 PM   #6
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ok, I need plan B snostorm. I tried mounting a few times and its still doing it, after following explicit directions.

It will still display F-- and only stop aperture down if I slightly loosen lens from camera mount (as if I am removing it)

Last edited by NMRecording; Sep 27, 2010 at 11:04 PM.
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Old Sep 27, 2010, 11:45 PM   #7
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sweeet, i kinda rigged it to work, for now. Not sure if this is what I shoulda did, but I found something to stick underneath the latch that drops down when the flange is moved over so that it would prevent it from dropping on the mount and locking it wide open.

Seems to lock on camera just fine and will actually let me move from F 2.8 to F32 /AE


id still love to hear your solution(s)
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Old Sep 28, 2010, 7:54 AM   #8
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Hi NMR,

Sorry, I've not been online much since writing the last post.

The problem with the Adaptall 2 PK/A adapter is that it sometimes doesn't allow a ground to the adapter for the body. Welcome to the world of Adaptall 2 lenses! I have 5 adapters and all of them needed this, to one extent or another. . .

Looking at the side of the mount that attaches to the camera body, you see the 3 electrical contacts at the bottom of the mount, then a small black dot to the left of the contacts, and then the end of a screw that is attached from the other side. Apparently they used a thread sealant on this screw and wiped off the excess, but this left a very thin invisible skin of what is essentially an electrical insulator on the metal.

Dismount the adapter since you don't want to get any shavings or stuff in the rear of the lens. Take a knife blade or a very fine abrasive and gently scrape the screw end and an area around it maybe 1/8 - 3/16" diameter. You want to clean the metal, but not cause a significant depression. All you're doing is cleaning off a virtually invisible coating of plastic. Blow off any dust or scrapings, and you should be done.

Remount the adapter and fit the lens on the camera. It should show you the aperture without fiddling. Try rotating the lens as far as the play in the lock allows in both directions, and the aperture should continue to be displayed. If it doesn't, repeat the cleaning procedure that you did, but extend the cleaned area out just a little bit larger. You should be able to get it to work perfectly with one or two tries.

Good luck with the 300/2.8. I think you'll like this lens. It's amazing what a really fast long tele is capable of.

Scott
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