that's not the reason, see my last post. Errors in aperture setting sensing and actual apetures at exposure are the reason why stop down metering will always be more accurate ( if even VERY slightly) than open aperture metering. JCO
-----Original Message----- From: Joe Wilensky [mailto:[EMAIL PROTECTED] Sent: Thursday, November 04, 2004 4:44 PM To: [EMAIL PROTECTED] Subject: Re: Stop Down Metering on K, M, LX I've seen discussion of this as a possible exposure factor only with the combination of both stop-down metering AND a camera that takes an average reading of the entire focusing screen, rather than a centerweighted reading. The idea is that lenses that vignette a bit wide open may cause slight inaccuracies in cameras that meter wide open and also take a full-frame average reading. Centerweighted meters give far less weight to the corners of the frame and this point is probably moot for those cameras. It's all probably quite insignificant. Joe >Shel Belinkoff wrote: >>Hi Christian, >> >>A couple of reasons. First, a week or so back JCO made the assertion >>that by metering thru a lens set at the taking aperture, measuring the >>actual light transited rather than having the camera essentially >>calculate the exposure, would result in a more accurate, or precise, >>exposure. I'd like to see if there's any truth to that, and if >>there's any practical difference. >> > >My guess would be that the difference would be so tiny as to be >insignificant. Esp with film since there is so much latitude. > >But if you are really interested in testing this, an interesting way >to do this would be to use Mark's trick with the *istD, that is, >mount the lens so that it is not fully locked, to a position such >that the lever that keeps the aperture wide open is not engaged. I >believe he said it was about 1/8 of a turn or so, but check with >him. This is ok for tests like you want to do, but I would not >recommend this for everyday shooting, as the lens is in somewhat of >a precarious situation not fully locked in and could fall off. > >>Also, I want to compare two similar lenses, one being a Super Tak that >>can only be used stopped down on K bodies and the other being a K >>mount version of the lens. It would seem that if the metering styles >>used were the same (assuming there IS any difference as suggested by >>JCO), the comparison between the two lenses may be more accurate. >> >>However, I doubt that I'd want to shoot that way when making regular >>photographs. >> >>Oh, there's a third reason: I've just a little too much time on my >>hands right now <LOL> >> >>Shel >> >>>[Original Message] >>>From: Christian <[EMAIL PROTECTED]> >> >> >>> > Is there a way to use a K-mount lens on the K, M, or LX bodies >>> with >> >>stop >> >>> > down metering instead of having to use open aperture? >> >> >>>Just a silly question, and forgive my ignorance, but why would you >>>want >> >>to?
