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12-05-2014, 07:11 PM   #1
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Aperture Value blank after mounting SMC F Lens

Keh did it again!!! This is the third time in a row I am getting a lens not as described... The lens is a SMC Pentax F 80-200 F4.7-5.6

This time I returned my D-FA 50mm 2.8 Macro the second time and got a cheap lens for 39 bucks in exchange. Never thought that would have a problem. Now when I load the lens on the camera, it does not show the Aperture value in any more. Its just shows it as F _ _ on the camera. I cleaned the lens and the contacts, but still it is not working and yes the Lens is set to the automatic Aperture setting. I tried my other lens they all seem to be fine.

I also took pictures and it seems to be setting max aperture setting as the pictures do come out well.. Anyone. The pictures have the Aperture setting in the EXIF Properties. Does anyone have any ideas what I could be missing.. I really hate calling KEH again consecutively the third time!!

12-05-2014, 07:22 PM   #2
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QuoteOriginally posted by donpjt Quote
I could be missing..
Did you rotate the aperture ring to "A" setting?
12-05-2014, 07:38 PM   #3
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QuoteOriginally posted by ultraviolet Quote
Did you rotate the aperture ring to "A" setting?
Yes, I did that. Even made sure that it clicked to the A setting..
12-05-2014, 07:50 PM   #4
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Probably a bad zoom/ aperture information brush. Does it make any ticking or grinding noises when you zoom.

12-05-2014, 08:44 PM   #5
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QuoteOriginally posted by Sliver-Surfer Quote
Probably a bad zoom/ aperture information brush. Does it make any ticking or grinding noises when you zoom.
No, I don't hear any noise while zooming..
12-05-2014, 08:49 PM   #6
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Sometimes it happened with my FA 50 1.7 (on the K20D) as well. Clean the contacts both on lens and body, cycle the aperture ring from A to anything set manually a few times and check again. This uded to help for me.
12-05-2014, 08:49 PM   #7
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Still likely to be bad info brush if it is clean
12-05-2014, 08:56 PM   #8
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Does the "A" pin extend in the "A" setting and retract when not? The "A" pin assembly may just need some cleaning. Even if it does extend some grease or dust in the works could keep in from making contact where it needs to under flange.

12-05-2014, 09:12 PM   #9
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QuoteOriginally posted by Not a Number Quote
Does the "A" pin extend in the "A" setting and retract when not? The "A" pin assembly may just need some cleaning. Even if it does extend some grease or dust in the works could keep in from making contact where it needs to under flange.
The A pin can be swung back and forth in A setting. Only in the fully open setting it remains fixed. ie, at F 4.7 I'm assuming the A pin is the one next to the inner barrel

---------- Post added 12-05-14 at 10:19 PM ----------

QuoteOriginally posted by Caver Quote
Sometimes it happened with my FA 50 1.7 (on the K20D) as well. Clean the contacts both on lens and body, cycle the aperture ring from A to anything set manually a few times and check again. This uded to help for me.
Thanks for the tip, I tried that as well.. but still not working
12-06-2014, 12:29 AM   #10
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This sounds extreme, but has worked for me on some old A series lenses and Tamron Adaptall-2 mounts; carefully scratch around the contacts with a sharp knife or razor. Alternately, do something else to remove invisible build up of crud preventing clean contact of lens to body. Do not use any liquid or paste, maybe very fine metallic sandpaper. If the lens and body are making a clean contact and you still have a problem there is no simple solution and you will have to take both to a technician.
12-06-2014, 02:54 AM   #11
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an eraser... I used it in the past to clean RAM contacts. Really does work well to remove oxids.
12-06-2014, 06:26 AM   #12
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Tried both the eraser and the knife scratch.. but didn't do the trick.. I guess its time to call KEH.... again....
12-06-2014, 06:47 AM   #13
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This happens with my 60-250 now and then. I notice it more when I'm using a teleconverter, but it happens without it, too. usually tapping the lens somewhat less than gently resolves it.
12-06-2014, 06:52 AM   #14
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QuoteOriginally posted by donpjt Quote
The A pin can be swung back and forth in A setting. Only in the fully open setting it remains fixed. ie, at F 4.7 I'm assuming the A pin is the one next to the inner barrel
The "A" p[n or contact is the only pin or contact on the lens mount that should change when you move the aperture ring to or from "A". On the "A" setting it should extend out from the flange about 0.5-1mm. With the aperture ring set at anything else the contact should be flush or slightly below the flange. The contact is spring loaded and will depress when pressure is applied to them. This is to allow you to mount or dismount the lens. The "A" series lens use a system of non-conductive plugs and the bare metal of the mounting flange. In this case the "A" contact will be the only contact with a rounded pin.

The position of the pins/contacts is illustrated on this webpage which gives some explanation on the function of the contacts:
http://www.robertstech.com/matrix.htm

If you have a multimeter or circuit continuity checker you can test to see if the pin is conducting properly.
12-06-2014, 05:34 PM   #15
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My FA 80-320 behaves that way, it's a known issue with my lens and only repairable if I want to open it and tinker. Here's hoping your problem is a bit easier to fix. You may be able to use the lens - mine is affecting the autofocus also, so I just use it as a manual focus manual lens.
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