On Sun, Dec 17, 2006 at 10:00:10AM +0100, Jens Bladt wrote: > But there are contacts on the Adaptall 2 mount for Pentax. > This will fit any Pentax KA bayonet and report the aperture setting to the > camera, which will work like any A-lens.
While there are contacts on the Adaptall 2 mount, they don't actually report the maximum aperture of the lens, because there's no way for the lens to communicate this information to the adapter. Instead they always report the same maximum aperture (f2.8), no matter what lens is mounted (or even, if I remember it right, when no lens is fitted). This doesn't matter most of the time - after all, every auto-exposure camera Pentax built prior to the introduction of the KA mount managed to perform perfectly well without knowing the maximum aperture of the lens. All you need to know is that when stopped down the lens will need so many more stops of exposure than the wide-open meter reading. I'm also a little dubious as to whether the Adaptall lenses were an exact match to the Pentax A lenses when it came to partial stop-down (i.e. controlling the aperture from the body, with the lens in the "A" position). I could have been worrying unnecessarily, but when I was really concerned about precise exposure I always used Av mode (especially if using the TC, which added another mechanical link). -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net
