PentaxForums.com - View Single Post - Faulty FA 80-320

Just1MoreDave · 07-01-2009, 11:42 PM

Originally Posted by EsBee

Thanks for the advice, but since I didn't pay too much for this lens, I am wondering if its even worth paying shipping and the repair costs.

But I can't get myself to throw away this big point-and-shoot lens, either. Even though I don't like not having any control over the aperture, its not impossible to get a few keepers.

I would see if it works as a non-A lens. Try setting the aperture ring to f11, the camera to M mode, use the green or AE-L button to meter and see if the shot is properly exposed. That would verify that the mechanical aperture functions work.

What is broken is most likely to be some electrical contact in the lens mount. Unfortunately there are a lot of electrical contacts in the lens mount. Most (as many as 6) tell the camera what the lens's aperture range is. They usually are brass or steel pins, with rounded ends that you see at the rear of the lens, insulated from the mount with plastic. On the inside, the pins get a lot smaller and have tiny springs loosely fitted on the small ends. Those springs rest on contacts when the mount is installed.

The probably broken one is unlike those, possibly just a spring that contacts the inside of the mount and an interior contact. It is mixed among the other contacts, but you can usually tell where it goes because the plastic insulator takes a jog to leave a spot where the spring can touch the mount.

You might be able to take the mount off, work out where this spring should go, get it back in place and reinstall the mount. The mount holds a lot of parts together, so you want to do it carefully in a clean, well lighted, controlled space to keep those parts in place. I have sometimes taped the contacts to the mount to keep them from moving, and taped the aperture ring to the lens to keep it from lifting off. I can do it now without those precautions but as long as the tape doesn't leave residue it won't hurt.

07-01-2009, 11:42 PM	#8
Just1MoreDave Pentaxian Location: Aurora, CO Gallery Photos: 1 Posts: 789	Originally Posted by EsBee Thanks for the advice, but since I didn't pay too much for this lens, I am wondering if its even worth paying shipping and the repair costs. But I can't get myself to throw away this big point-and-shoot lens, either. Even though I don't like not having any control over the aperture, its not impossible to get a few keepers. I would see if it works as a non-A lens. Try setting the aperture ring to f11, the camera to M mode, use the green or AE-L button to meter and see if the shot is properly exposed. That would verify that the mechanical aperture functions work. What is broken is most likely to be some electrical contact in the lens mount. Unfortunately there are a lot of electrical contacts in the lens mount. Most (as many as 6) tell the camera what the lens's aperture range is. They usually are brass or steel pins, with rounded ends that you see at the rear of the lens, insulated from the mount with plastic. On the inside, the pins get a lot smaller and have tiny springs loosely fitted on the small ends. Those springs rest on contacts when the mount is installed. The probably broken one is unlike those, possibly just a spring that contacts the inside of the mount and an interior contact. It is mixed among the other contacts, but you can usually tell where it goes because the plastic insulator takes a jog to leave a spot where the spring can touch the mount. You might be able to take the mount off, work out where this spring should go, get it back in place and reinstall the mount. The mount holds a lot of parts together, so you want to do it carefully in a clean, well lighted, controlled space to keep those parts in place. I have sometimes taped the contacts to the mount to keep them from moving, and taped the aperture ring to the lens to keep it from lifting off. I can do it now without those precautions but as long as the tape doesn't leave residue it won't hurt.