OK, so I fixed the major problem, but it seems that I still have the other problem that I detected when examining the first. In A-mode, the lens diaphragma is a bit smaller (about one stop, I guess) then what the camera says.
No big deal, but I'd like to understand what's going on. This looks more like a mechanical problem that won't be solved by CLA? Any ideas? How does the A-mode work? I imagine it's like this: - inside the camera body, I see a litter lever that engages the diaphragma control lever on the lens. - when in M-mode, the lever in the camera body just moves all the way up (releases the diaphragma to close, but the lens mechanics will stop it at the f-stop selected on the lens); after exposure, the lever in the camera body moves down again, and pulls the lens diaphgragma open - when in A-mode, the lens allows the diapragma to be operated completely by the lever, so it's the camera that controls how far the lever is moved upwards, and thus how much the diaphragma is allowed to close. Reasoning like this, I'd rather expect the cause of the problem to lie within the camera... Can anyone second that? Groeten, Vic Vic Mortelmans schreef: > Hi, > > this was easy!! > > I went to a shop that does camera maintenance, and they estimated 75 > euro for the job --- more than the lens is worth. So I was lucky: a good > reason to take a look at the inside of the lens without the risk of > destroying value. > > There was nothing wrong with the blades (as I expected, because oil on > the blades should be visible, shouldn't it?), but there was oil in the > mechanism. See the picture here: > > http://picasaweb.google.be/vicmortelmans/Tech/photo#5076727091233563442 > > It shows the back of the lens with the mount removed (only five screws > and one loose ring, no tiny bits jumping allover the room). The red line > indicates the two sliding parts that had oil inbetween them. Applied > some aceton and now the diaphragma closes as snappy as it can get. > > Groeten, > > Vic > > > Vic Mortelmans schreef: >> Hi Mat, >> >> You're right. The blades are not 'snapping' together when releasing >> the switch. I compared to my SMC M 28 f:2.8, which behaves a lot more >> 'snappy'. >> >> I never sent a lens out for CLA... what would be a reasonable price >> for this job? Any chance of trying this myself? >> >> Groeten, >> >> Vic >> >> >> Mat Maessen schreef: >>> On 6/15/07, Vic Mortelmans <[EMAIL PROTECTED]> wrote: >>>> The shots on part 2 are all overexposed... >>>> >>>> I don't use program mode that often (mostly aperture priority), so >>>> could >>>> it be that this mode is malfunctioning? The diaphragma control by the >>>> camera is certainly doing something; I did a quick test in shutter >>>> priority mode and saw the diaphragma change when selecting different >>>> shutter speeds. >>> >>> Most probably, your A50/2 need a CLA. The diaphragm blades are most >>> likely not closing down quickly enough. You can test this manually, >>> by looking through the back of the lens, and toggling the aperture >>> lever manually with your finger. The aperture blades should snap >>> closed when you release the lever, and you shouldn't feel any >>> stiffness or resistance in the lever motion (set the lens to f22 or A >>> for this test). >>> >>> -Mat >>> >> > -- PDML Pentax-Discuss Mail List [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net
