YOU are the one confused here. ALL autoaperture M42 lenses have "open-aperture auto aperture" (your term, not mine), that's what auto aperture ISs by defintion. The lens aperture stays open all the time during focus and composition and only stops down during the moment of exposure. It then reopens immediately and automatically after the exposure is made. The vast majority of M42 lenses are auto apeture models. Yes, there are/were some presets, some semi-automatics, and some manuals with regards to the aperture function but the vast majority of them (M42) are full auto-aperture.
The reason I say you are confused is you are associating the metering directly with the autoaperture ( someone else was doing the same thing too, but its a mistake ) because the metering technique is independent of the auto aperture function. Most M42 bodies do stop down metering, but this is only temporary, during the metering function itself, and the lens goes back to normal autoaperture functioning once the proper meter reading is made ( if the body even has metering, or you choose to use it, or choose to take another meter reading). OPEN APERTURE METERING- which is what I think you are referrring to ( which is not the same thing as auto apeture), is where you can take meter readings without stopping down the lens. That is not as common as autoaperture, but it is not as needed or useful as autoaperture is either. All open aperture metering lenses have autoapeture function too, but not all autoaperture lenses have open aperture metering function. I am not advocating a dedicated M42 DSLR be produced for open aperture metering, I am advocating one to get the AUTOAPERTURE function, which most M42 lenses support, and which is sorely lacking when you mount M42 lenses on any current DSLR including Pentax's via a M42 mount adapter ring. jco -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Cory Papenfuss Sent: Wednesday, February 21, 2007 4:01 PM To: Pentax-Discuss Mail List Subject: RE: 85mm f1.8 SMCT on ebay : $400+ > =============================================== > NO, I wasnt confusing the two, I was taking > both into consideration. Its not a complex > a mechanism to DEVELOP or MFG. Far simpler > than the rest of the camera, which wouldnt > even need changing. If it's so friggin' simple, why don't you just do it and let us all know when we can buy your camera at Wal-Mart. No, its not as simple as > the cam sensor for K/M lenses would be, but in > my opinion the benefit of the M42 camera (AUTO > APERTURE) is not minor and far more important > than the K/M aperture sensor would be for K/M > lenses would be for PK DSLR bodies. Its a MAJOR > MAJOR MAJOR flaw to not have autoaperture function, > far worse than limted meter or Lack of AF would > ever be. > jco > =============================================== > So exactly what functionality does an auto-aperture M42 lens/body combination have that is not gained by an aperture coupler in a K-mount? IIRC, there aren't many of the millions of M42 lenses out there that have open-aperture auto aperture. Most are auto/manual stop-down metering. -Cory -- ************************************************************************ * * Cory Papenfuss, Ph.D., PPSEL-IA * * Electrical Engineering * * Virginia Polytechnic Institute and State University * ************************************************************************ * -- 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
