I thought the difference was:
On K M lenses the aperture lever movement is full on and aperture area
is determined by setting of fstop ring
On A lenses, same as K M lense when not set to "A" setting on fstop ring
when set to "A" on fstop ring, aperture area is controlled by linear
movement
of aperture lever.
jco
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On 9/17/2014 10:02 PM, Mark Roberts wrote:
Zos Xavius wrote:
Ricoh claims that the aperture mechanism used in the M/K series is not
accurate. My experience with green button stop down metering tells me
that there might be something to that given the liberal amounts of EV
compensation I end up using with various lenses. Oddly wide open
meters fine with the green button. Hmmmm.
With A-series and later lenses the aperture lever movement is linear
with respect to aperture area; with the K and M series lenses the
movement is linear with respect to aperture *diameter*, which makes
them much more dodgy (and is why Pentax changed it in 1982).
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