Igor, There is a slight difference in the linearity of the actuator movement on the A and later lenses. The Super A/Super Program and later cameras (but not the LX) anticipate using this more linear scale. (That means everything from P3's thru SF1's thru PZ-1p's thru the K10D.)
The older K and M lenses had a bit of non-linearity in the movement of the aperture lever and the K and M series cameras anticipated that. When they added the "A" setting, Time-Valued automation became possible, not just the traditional Aperture-Valued automation on exposures. Pentax accomplished this with a more linear set of aperture lever movements/settings. I suspect it was less fiddley to F6.1 is x% of the way open vs y% between f 5.6 and f 6.3. In practice, I've wondered about it, but never been able to notice any difference in the slides my cameras produced with "A" vs K or M lenses. I always attributed any differenced to the light transmission qualities of the lens itself. Regards, Bob S. On 3/26/07, Igor Roshchin <[EMAIL PROTECTED]> wrote: > > > Hello! > > Sorry for bringing up this question that may be known to most > of the people here. I just realized that I don't know it, and couldn't > find the information on the KMP site or elsewhere on the web. > > This question is about aperture control design. > For the A and later lenses that have "A" setting on the aperture ring, - > what is the step of the actual aperture setting in this mode? > If it doesn't coinside with F-stops or 1/2-F-stops, then is it > body-dependent (i.e. is one body more capable to utilize > sub-1/2-f-stops then another) or is it standardized? > > I realize that the motion of the diaphragm actuator in the lens is > stepless, so it is up to the body to choose the steps, if any > (is it determined by the DAC bitness?) > > Thank you, > > Igor > > > > > -- > PDML Pentax-Discuss Mail List > [email protected] > http://pdml.net/mailman/listinfo/pdml_pdml.net > -- PDML Pentax-Discuss Mail List [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net
