Ah, but it is open aperture. The second metering after stop-down is merely for confirmation that the aperture was selected correctly.
-Adam J. C. O'Connell wrote: > Its not open aperture either which is a big > Difference too and wont even work at all > In low light with smaller fstops ( meter sensitivity > is sucked away by stop down method at small stops. ) > jco > > -----Original Message----- > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of > Adam Maas > Sent: Sunday, October 22, 2006 8:37 PM > To: Pentax-Discuss Mail List > Subject: Re: Some observations on lens mount capability. > > If the aperture is set to minimum, you get Programed AE. It follows the > program line. And you only get an extremely short delay to teh firing of > > the shutter (Which is exactly the same delay you get with any camera > using pe-flash based TTL flash, like all P-TTL pentax bodies). > > So yes, this is Programmed AE. It's just not as elegant as pentax's > solution. > > -Adam > > > J. C. O'Connell wrote: >> I do not understand what you have posted. >> How can the camera set the aperture when >> Its turned by hand? If you just leave >> The fstop at minimum all the time you >> Are not really getting true program operation >> If the fstops are approximate, metering is stopped down, and you >> Don't get instant exposure when you fire >> The shutter LIKE PENTAX DOES. They may be >> Calling that programmed AE but its not >> The same as pentaxes programmed AE which is much better >> And without those degradations. We are talking >> About two different modes here with the same name >> Which is bad. Blame that on Chinon if they >> Call it the same as pentax's programmed mode. >> jco >> >> -----Original Message----- >> From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf > Of >> Adam Maas >> Sent: Sunday, October 22, 2006 5:19 PM >> To: Pentax-Discuss Mail List >> Subject: Re: Some observations on lens mount capability. >> >> Funny, but my Chinon CP-6 does programmed exposure (with two seperate >> selectable program lines) with K/M lenses. >> >> It does this by selecting the desired aperture, attempting to set it, >> then remetering to confirm. >> >> The Nikon FA does the same thing with AI and Ai converted lenses in >> Program and Shutter priority modes. AI lenses are functionaly > identical >> to K/M lenses apart from their ability to mechnically communicate >> maximum aperture (the FA is one of two bodies which takes full > advantage >> of that to allow matrix metering). >> >> So reality proves you wrong. >> >> -Adam >> >> >> J. C. O'Connell wrote: >>> K/M lenses cannot support programmed >>> Exposure modes because in programmed >>> Exposrue modes the camera choosed the >>> Fstop and the shutter speed based on >>> Light condtions. K/M lenses cannot >>> Have their fstops set by the body because >>> They lack the consistant linear stop >>> Down levers ( even non-linear compensation >>> Wont work because the lensse are inconsistant >>> If you try to stop them down by partially >>> Actuating the stop down lever). >>> >>> IF it were possible pentax wouldn't have >>> Bothered with A series lenses. >>> jco >>> >>> -----Original Message----- >>> From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf >> Of >>> Adam Maas >>> Sent: Sunday, October 22, 2006 4:23 PM >>> To: Pentax-Discuss Mail List >>> Subject: Some observations on lens mount capability. >>> >>> I've been thinking about exactly what K/M lenses are capable of, and > a >>> few asides. >>> >>> First off, you can do at least Program mode with K/M lenses. In fact > I >>> own a camera that offers this with K lenses(Chinon CP-6 Dual Program) > >>> and another that does this with the functionally identical Nikon AI >>> lenses (Nikon FA). Shutter Priority is also possible if you are >> willing >>> to override shutter speed selection in some cases (the Nikon FA does >>> this with AI and earlier lenses) in both cases the camera double >> checks >>> the metering after stopping the lens down, the FA will override >> shutter >>> speed selection by up to a stop in either direction to compensate for > >>> non-linear apertures, this only occurs at small apertures though. An >>> interesting capability of the CP-6 is you can limit the smallest >>> aperture the camera will select in program mode with the aperture >> ring, >>> the FA requires aperture to be set to minimum to work in P and S >> modes. >>> So Pentax has never chosen to take full advantage of the automation >> that >>> is technically possible with K/M lenses, even if they weren't > designed >>> with this in mind. >>> >>> Nikon has never produced an AF body that fully couples with AI-S >> lenses, >>> the F4 is the only one to fully couple with AI lenses. In fact Nikon >>> only ever made one camera that takes full advantage of the AI-S > mount, >>> the FA. And Nikon is the only other maker with reasonable backwards >>> compatibility with its SLR mount, but it hasn't fully supported it's >> MF >>> mount since 1989 (when the FA was discontinued). >>> >>> -Adam >>> >> > > -- PDML Pentax-Discuss Mail List [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net
