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12-19-2007, 09:09 PM   #1
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A setting not working

I recently picked up an FA 80-320. I am not able to get the a setting to register any aperature reading. Has anyone experienced this before? any thoughts?

12-19-2007, 09:28 PM   #2
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First thing to check is that the aperture ring is set to the "A" position.
12-19-2007, 10:08 PM   #3
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QuoteOriginally posted by Ole Quote
First thing to check is that the aperture ring is set to the "A" position.
And the second thing to check, if the "A" setting is not the problem, is the cleanliness of the contacts. A little rubbing alcohol will do wonders.
12-20-2007, 07:59 AM   #4
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Yes to the first, and I have cleaned the contacts with no improvement.

The contacts have been my original suspicion. One of the five (the end one on its own) does not seem to protrude or have the "springiness" that the others do. Can anyone verify if this one does have to do with the A setting?

12-20-2007, 10:49 AM   #5
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QuoteOriginally posted by billhardie Quote
Yes to the first, and I have cleaned the contacts with no improvement.

The contacts have been my original suspicion. One of the five (the end one on its own) does not seem to protrude or have the "springiness" that the others do. Can anyone verify if this one does have to do with the A setting?
You need to be very specific about the contact in question.

Are you discussing on the camera body or the lens.

On the camera body itself, starting at the lens locking pin, the third counter clockwise from the locking pin shoud be down. It is a deliberately recessed pin, not a protruding pin. This is done so that the camera can detect a manually set apature. If this pin were to contact the body of the lens mount, that connection would signal to the camera the lens set in the A position. All other contacts are spring loaded and extend beyond the surface of the mount.

On lenses depending upon type, minimum and maximum apature etc, you will have many different pin arrangements. what is important on the lens, is the corresponding pin to the recessed pin on the body. it should, (by using an ohm meter) be a low resistance to the lens mount when set in the A position and a high resistance open circuit) when not in the A position. This contact (if all locations have pins at about 1/8 inch (3mm) spacing, is the 5th clockwise from the locking hole, or 3 counter clockwise from theopposite end.

If you check the resistance of this pin to lens base in both the A and other positions, you can determine if it is the internal switch in the lens, or the contacts. This poin shoudl be spring loaded and "proud" i.e. sticking up
12-20-2007, 12:53 PM   #6
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Lowell,

Thanks for the info. I have attached a picture of the lens with an arrow pointing to the contact in question. This is the one that seems to be different from the others. But if I am understanding you correctly it is not that one that would control the A setting.
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12-20-2007, 01:03 PM   #7
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QuoteOriginally posted by billhardie Quote
Lowell,

Thanks for the info. I have attached a picture of the lens with an arrow pointing to the contact in question. This is the one that seems to be different from the others. But if I am understanding you correctly it is not that one that would control the A setting.
You are correct, that pin is one of 5 used to carry the min/max apature information to the camera. It may be that loss of this contact causes the camera to consider an incorrect / impossible combination.

It is the pin immediately to the left of that one (i.e. after the blank location) which is controlled by the A position.

That pin is spring loaded and should stick out. It is easy to fix if you have patience and a lot of little parts (springs etc) and a lot of patience. Otherwise if the lens is important to you get a shop to do it.

I learned about what went into these contacts and the mounts when I converted a K to KA mount.
12-20-2007, 01:22 PM   #8
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So in your estimation, that pin is likely the culprit?

Any guess on what a shop may charge for a repair like this? I am tempted to open it up and give it a try but looking at diagrams of these lenses has me a bit apprehensive.

12-20-2007, 02:33 PM   #9
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QuoteOriginally posted by billhardie Quote
So in your estimation, that pin is likely the culprit?

Any guess on what a shop may charge for a repair like this? I am tempted to open it up and give it a try but looking at diagrams of these lenses has me a bit apprehensive.
I would expect some standard shop charge. (1-2hours at what ever rate) plus parts. I don't know whether they would replace the entire contact block for example, or just a spring.

I guess the other real issue is what testing they would do to confirm the problem fixed.

I took a sigma lens of similar vintage apart, and it is relitively simple the only thing to watch, and this will depend upon each maker, is how the apature detents are achieved. on the sigma lens this was a spring loaded ball against notches in the back side of the lens mount. It took a while to find the spring again.
12-20-2007, 02:42 PM   #10
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Thanks Lowell for your help.
12-20-2007, 03:59 PM   #11
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It's not exactly common but here are quite a few reports of this problem on the web (I've seen a couple of cases myself in used lenses) and it always seems to be the FA 80-320 that is involved (usually the black version).

I don't have a solution other than send it for repair so this probably isn't very helpful, but you are not alone..

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12-20-2007, 04:45 PM   #12
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Dave,

Mine is the black version and I have seen a couple of similar reports as you mention. It won't be the end of the world as I don't care about the auto too much but if the fix is simple I will probably do it.
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