I had an A* 300 f/2.8 that had a problem with the aperture cam/lever control/or? sticking wide open. Got some terrible over exposures. Send it to Pentax for repair. When I got it back, I gave it a try by hand before mounting it and it stuck. Tried it several more times and it did not stick again. Used it for several years after that and had no problem. At least I had no problem images tell me so. Have you tried working that aperture linkage by hand to check if it's working freely?
Jack ----- Original Message ----- From: Tom C <caka...@gmail.com> To: pdml@pdml.net Cc: Sent: Friday, April 27, 2012 3:34 PM Subject: Re: 100/2.8 Macro Issue - Thoughts? > You don't say if you are using the F, FA, DA or DA WR version. My > FA100 will sometimes refuse to get a focus lock and sit at infinity. > I press in the mount lock button to release the AF drive and manually > focus to approximate focus and it then seems to work ok till the next > time it decides it can't focus on what I'm asking it to look at and I > do the same thing. It's done it on all the digital cameras I've owned > *istD, K10, K7 and K5. I can't remember it doing it on the MZ-S, but > that doesn't mean it didn't. > > I don't know if this helps you or not. I don't use it much now days > and usually only on manual focus as I have the DA WR version for field > work (smaller and weather resistant is good when knee deep in sea > water). > > Leon Yeah that was stupid of me. It's the tank-artillery-shell-bodied FA/100 2.8 Macro. It seems to be related to the aperture lever/control on the lens. It appears through the viewfinder that it's totally stopped down in 'A' mode, even when the camera body says f/2.8, f/4, etc. Setting the lens manually to a big aperture allows it to AF (viewfinder brightens), then resetting it to 'A' mode, viewfinder continues to appear bright and AF continues to work. Take the lens off the body, put it back on, same issue repeats. Thanks Leon, et al. > >> On Apr 27, 2012, at 4:13 PM, Tom C wrote: >> >>> I've started having problems with this lens that are weird. I don't >>> think it's operator error... >>> >>> It didn't want to AF last time I had it on (was using more as a >>> telephoto). I just mounted it again, and had the same issue. It seems >>> to hunt a bit but does not achieve focus and stops. >>> >>> It was on the 'A' setting and the view through the viewfinder was very >>> dark. I turned the aperture ring to 2.8 and voila it focuses. I then >>> returned it to 'A' and it focuses with no problem, as it always has, >>> regardless of what I set aperture to via the body. >>> >>> However, if I take the lens off the camera, and put it back on, it's >>> behavior goes to as stated earlier, it doesn't want to focus. I've >>> repeated this half a dozen time and it's the same each time I try it. >>> >>> Idea's? >>> >>> Tom C. -- PDML Pentax-Discuss Mail List PDML@pdml.net 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 PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
