Basically the camera doesn't recognise the fact that the aperture ring is in the "A" position, so I can't use shutter priority modes.
Do you have other F/FA lenses to test and see if it's the lens or camera problem?
As far as I can tell this isn't true for later (F and FA) lenses, so I assume the switching is done elsewhere in the lens, rather than by moving the contact.
You are correct. F/FA lenses are different. There is a "brush" (what they called in the manual) which closes and opens the circuit when you switch the lens in & out of the 'A' position, locates underneath the lens mount. That brush is delicate and may be bent or something related to it. However, it is unlikely to happen for no reason. Has the lens been dropped or stripped before?
> Can any list member confirm or deny this hypothesis? I haven't > seen my multimeter for years, so I don't know whether I'll be able > to do any further checking myself.
I suggest you try other F/FA lenses before you do anything crazy. The brushes (one for aperture, one for distance info) in these lenses could be destroyed easily if you don't know the proper procedure.
> I'd also like to know what the likelihood is that this could be > something I could repair myself, something a typical neighbourhood > camera repairer could fix, or something that will have to go back > to Pentax.
If the brush contact is dirty or coated with grease (and that part of the lens is greasy on purpuse), the fix is easy. Just remove the mount, clean the contacts, and the assemble. But "clear" threadlock should be applied to the lens mount screws, and the proper one is "Threebond 1401" (can be found in Fargo). But the smallest bottle is 200g which is quite big. If the chip is fired, the whole circuit must be replaced (but this must be very rare). The job is not very difficult if you know how, but not recommend if you haven't done it before. Which lens are you talking about btw? :-)
Alan Chan http://www.pbase.com/wlachan
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