With the F-series Pentax introduced a chip storing the MTF data for each individual lens. So with F or later the camera knows what opening and thereby speed thats gives best resolution. When the camera knows this, it has an easy task setting optimal exposure values including ISO.
This concept might be improved with the DA series. Third part lenses and lenses older than F-series don't have that chip. Tim Typo Mostly harmless (just plain Norwegian) -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Roman Sent: 13. april 2007 14:51 To: [EMAIL PROTECTED] Subject: Pentax DA lenses/body interaction vs. third party lenses I don't know whether you'd noticed that camera body interacts with DA lenses in a different, more logical way than with third party lemses. For example, my DA 50-200mm with auto iso 200-800 switches ISO speed whenever shutter is slower than 1/200 for selected apertures in AE priority, while with Tamron I had to keep an eye on exposure or chose Tv mode to keep reasonable shutter speed or use tripod. Seems like pentax bodies had some sort of behaviour pattern for each recognized DA lense. I haven't noticed such behaviour with older FA lenses. Anyone has had noticed this too? -- new photos ever so often... <http://roman.blakout.net/> -- 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
