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02-05-2009, 03:04 PM   #1
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How does the 'A' position on an FA lens work..

Just bought an FA series 80-320 lens from ebay.
When using it on the K10D, with the Aperture ring set to 'A' I'm finding that unless i apply light pressure, holding the ring turned against it's maximum rotation - the lens does not work on the camera.

What does the 'A' position do within the lens - is operating a mechanical linkage, or operating a microswitch?

Any idea what the repair cost is likely to be?


02-05-2009, 03:47 PM   #2
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When the aperture ring is set to "A" it engages the electrical comunicacion between lens and body. If your lens is not doing it or doing it with having tu push the ring further, it means there is a faulty contact (microswitch type). Sometimes by just moving the aperture ring back and forth (that is... from A to closest aperture) several times may fix this faulty contact. Give it a try.

In the meantime, if it doesn't work, adjust body's custom function to allow use of aperture ring and use your lens manually untill you can find someone to fix this. Dont really know how much it will be to repair it, but for sure, it won't need parts, just a good cleaning probably.
02-05-2009, 06:04 PM   #3
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on my FA 28-80 and FA28-105 the A pin (3rd from the lens locking pin) is a switch activated pin. Early KA lenses were (I believe) a mechanical pin that moved down to contact the recessed pin in the body.

It may be that the spring in you rlens is a little tired, or the pin is dirty. You can clean it with a gum/pencil eraser.

If the fault is in the switch, that requires disassembly of the lens mount, and the apature ring. watch out, it is loaded with tons of little springs that may fly about.
02-05-2009, 11:43 PM   #4
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Thanks guys.. gives me something to go at..

I'll not be dismantling it.. I'm going to speak to a repair shop today, if cleaning the pins doesnt work.


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