On Sat, May 10, 2008 at 12:03 AM, Bob Sullivan <[EMAIL PROTECTED]> wrote: > Bill, > > I've found some exposure error as well with K and M series lenses and > the green button. > Somebody else mentioned it, and I don't understand it? >
> > On Fri, May 9, 2008 at 8:56 PM, William Robb <[EMAIL PROTECTED]> wrote: > > One of the guys on the Pentax Dysfunctional Web Forum chalenged me to test > my K20 exposure > > system > I thought the green button closed the aperture down and measured > light > exposure values. > I can't imagine how this is off, but here is an example with K35/2 lens. > (The lens was set at different apertures and green button pressed > before exposure.) > > http://picasaweb.google.com/rf.sullivan/K352ApertureTestOnK20d > > As you move away from wide open (f2) to smaller apertures (f12.8), > light moves toward overexposure. > (You can see more light in the big shadow on the right.) > This did the same with an M400/5.6 although I didn't post the details. > > All I can figure is that it has something to do with the aperture > lever being linear. > Since the A lenses (and later), the movement has been linear. > With the earlier M and K lenses, the movement is non-linear. > Is it possible that the K20D measures the right exposure, and then > sets a matching A lens aperture, > not closing the lens all the way down to the f12.8 we have set? > > Regards, Bob S. > One issue I noted is that it's surprisingly easy to drop the meter out of its range when shooting in anything other than daylight. -- M. Adam Maas http://www.mawz.ca Explorations of the City Around Us. -- 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.
