----- Original Message ----- From: "Antonio" Subject: Re: *ist series support for setting the aperture on the lens(was: ist D AE mode for K & M lenses)
> Ahhh, I see. So the lever on a K/M lense is not exactly the same as the > lever I see on my A lenses? The levers on the lenses are the same. There is a lever in the camera body that mates to one of the levers (right side when facing the camera front) which mates with one of the lens levers. On the istD and a few of the film cameras, this lever (it's called an aperture simulator or aperture estimator) is missing. This removes any way for the lens to impart aperture information to the camera via mechanical means. Since pre A series lenses lack the ability to transmit such information electrically, metering operation is compromised. Also, the camera cannot give a readout of what aperture value is chosen. By adding "green button metered manual" to the camera's firmware, a means of metering with the lens has been created. Note, it is not really a manual mode, but a stop down aperture preferred automatic. In operation, the camera is set to manual exposure, the aperture desired is chosen, and the green button is pushed. This stops the lens down momentarily, the camera meters the scene at the shooting aperture and sets the shutter speed accordingly. It is pretty easy, and not really as big a deal as it's made out to be. It would be nice if full K mount implementation was there, but the lack of it does not turn the camera into a peice of shit. It just means that support for lenses that are more than 30 years old has been implemented differently, and definitely was done as an afterthought. William Robb
