The circuitry, such as it is which is basically tiny brass balls shorting or not shorting to the frame or one of the other balls, is directly below the rear mounting ring. If you take that off, do it slowly so that you can see which balls and springs go where. It could be something gunked up in there. There is no real circuitry inside the old A lenses AFAIK. (I have had several apart, and successfully reassembled them)
Gerrit wiggle the lens in the mount; turn it off & dismount & remount the lens; turn it off & dismount the lens, clean the contacts on the lens & body and remount the lens ... When I turn it back on, maybe I'll get the focal length prompt again or maybe I'll get the last aperture I selected. If I *DO* get the aperture, it appears I'm going to get the "F--" again after a few shots. It's definitely something going on with the lens. I've tried it with a bunch of other lenses that have the aperture ring & an 'A' detent. They all work just fine. I've seen that "F--" before with several different lenses and it's always been when I somehow got the lens unlocked from the 'A' detent. As soon as I get the lens back in the 'A' position the problem goes away. I think something inside this lens that has to do with whatever circuit detects whether the lens is mechanically locked into the 'A' position or not is wearing out. On 7/15/2013 4:24 PM, Bob Sullivan wrote: > And John, > Did you clean the contacts on the camera as well? > Regards, Bob S. > > On Mon, Jul 15, 2013 at 12:40 PM, John <[email protected]> wrote: >> On 7/15/2013 1:03 PM, Zos Xavius wrote: >>> >>> Did you try cleaning the contacts? There isn't an communication >>> between the lens and the camera for an A lens. It just reads the >>> contacts and determines aperture range. Try cleaning them. >>> >> >> Yup. That was something I learned from Army radios. >> >> Don't know why it stopped working. Don't know why it started working >> again once I got home. Don't know when it's going to decide to crap >> out again. >> >> But the contacts are clean. >> >> I (gently) racked the aperture ring several times from 'A' to 2.8 & >> back again to see if maybe some bit of grunge was keeping it from >> registering the 'A' position internally. >> >> I guess it's time to start looking for a backup/replacement before it >> fails for good. Looks like the only thing available is going to be >> either the 28-70 F2.8 SIGMA EX ASPHERICAL (77) or the 24-70 F2.8 >> SIGMA DG EX ASPHERICAL (82). >> >> Anyone have hands on experience comparing either of them with the >> Tokina ATX-Pro? >> >> >> >>> On Mon, Jul 15, 2013 at 12:59 PM, John <[email protected]> wrote: >>>> >>>> I finally dredge up enough motivation to actually go out and do >>>> some photography. Got on site & my favorite lens takes a crap on me. >>>> >>>> My workhorse has been a Tokina ATX-Pro 287 28-70mmf/2.8. I got two >>>> frames & camera won't fire the shutter. Aperture shows "F--". I do >>>> everything I can to make sure the lens is properly seated & that >>>> the aperture ring is latched into the 'A' position ... NO JOY! >>>> Nothing I can do will make it show the aperture. >>>> >>>> I have one other 'A' lens (SMC Pentax-A Macro 1:2.8 100mm) in my >>>> bag on site, & when I switch to it the aperture works fine. I also >>>> try both lenses on my K10D (backup) and get the same results; >>>> Tokina "F--" & Pentax shows the aperture selected with the >>>> thumb-wheel. >>>> >>>> I'm back home & I've got a couple of other Pentax auto-focus 'A' >>>> lenses to test with. They all show the aperture & change with the >>>> thumb-wheel. And just to add insult to injury, I give the Tokina >>>> one last try & now it's showing the aperture again. >>>> >>>> Meanwhile, every bit of motivation has drained away! >> >> >> -- >> PDML Pentax-Discuss Mail List >> [email protected] >> http://pdml.net/mailman/listinfo/pdml_pdml.net >> to UNSUBSCRIBE from the PDML, please visit the link directly above >> and follow the directions. > -- PDML Pentax-Discuss Mail List [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions. -- PDML Pentax-Discuss Mail List [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
