I got it. The problem was I was playing with an old m42 super tak set on manual and it stops down when on the camera or not. I'll try an M lens when I get home.
Steven Desjardins Department of Chemistry Washington and Lee University Lexington, VA 24450 (540) 458-8873 FAX: (540) 458-8878 [EMAIL PROTECTED] >>> [EMAIL PROTECTED] 03/18/03 04:22PM >>> Hi Steve, see, I'm not gone yet... 3:-) > Stupid question. I've read that an M lens on the *ist will only > meter wide open. If the camera can't talk to the lens, how does > it know what wide open is? and if its reading the light coming > through the lens, why won't stopping down affect metering? Take a lens in your hand. Set it to f/16. Look through it to make sure that the aperture blades are closed. Not mount the lens on a camera body. Look through the lens again. The aperture blades are not there, since the body has opened the aperture. Now, set the exposure time to about 1/4 second or so. Make a picture while looking through the lens. See how the aperture blades closed for a/4 second? Now think about it. The camera meters before the shot WHILE THE APERTURE IS OPEN. While the image is being taken the aperture is closed. A _REAL_ camera meters through the open lens but calculates how much the lens will close and adjusts the exposure time (makes it longer). The *ist lacks one of the aperture couplings, so it doesn't know how much the lens will close during the exposure. It doesn't recalculate the exposure time and the image is underexposed. If the lens was, by chance, set to its maximum aperture, the error is 0 EV, and the image is properly exposed. HTH, Boz
