I believe the issues surfaced when using lenses with a large maximum aperture (such as a 50mm/f1.4).
Although Pentax never explained exactly what was happening, the most plausible hypothesis I saw was that the exposure metering in the K10D (and, I would assume, in later cameras) had some sort of compensation curve for the metering system based on the maximum aperture of the lens (presumably because of known problems with light hitting sensors at an oblique angle). An 'M' lens does not communicate maximum aperture (or the aperture to be used) to the body, so the exposure correction would not be performed (or would be performed using one fixed value for all 'M' lenses at any aperture). I didn't pay too much attention to the issue, because I decided to go with 'A' or later lenses back in '95 when I got my PZ-1p, so I rarely put an 'M' lens on any of my later bodies. And, in any case, I don't assume the metering on any DSLR is going to give me as good control of the exposure as I can get by looking at the histogram. The "green button" metering technique should get you close; just be prepared to apply some exposure compensation if you want it spot-on. That was necessary (at least with the *ist-D and K10D) anyway; from what Paul Stenquist says the K-7 may do rather better in this regard. On Mon, Sep 13, 2010 at 08:35:49PM +0200, Jens wrote: > > I may be using my M lenses too little. But I have never noticed any exposure > problems - except for those caused by the well known "slow aperture syndrom", > occuring when lenses are left unused for too long - or stored with open > aperture blades (on a camera or otherwise). > > I use a Seikanon wide angle macro lens quite often - which works like an M > lens. It's an absolutely brilliant lens - which I believe is made by a > company related to the later so well known Seiko brand. No exposure problems, > that I know of. Razor sharp. > > Regards > Jens > -- > Treat others as you would like to be treated yourself. > > On Sep 13, 2010 19:02 "Steven Desjardins" <drd1...@gmail.com> wrote: > > I've never really used an M lens on a Pentax digital, but I'm thinking > > about buying one. I know the green button trick, but how well does it > > actually work? Metering OK and all that? > > > > -- > > Steve Desjardins > > > > -- > > 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. -- 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.
