hi, when pentax switched from screwmount to K mount, THE MOUNT CHANGED in major ways and there was a gain, a newer faster to change lens mounting and dismounting system.
This is not the current situation with K/M lenses on their DSLRS. the mount hasn't changed and there is no new lens feature. To elaborate on the screw to K changover. Pentax used the same registration distance (45.5mm) and a larger body throat so that a ring could be installed and screw lenses mounted without any meter coupling or aperture activation. NOW HERE IS A MAJOR DIFFERENCE- between then and now, they could have made K bodies screwmount compatible with either or both the metering and apeture operation with screw lenses but it would have been extremely complex mechanically and extremely costly to do so. That decision was logical and economical and there was the gain of the new bayonet mount. This K/M DSLR situation is totally different, it's a really simple dirt cheap part and there isnt any new feature gained, no real cost savings, or change the lens mount. That's why I say its total B.S. to leave important and valuable but virtually free it so cheap part out at this time.... JCO -----Original Message----- From: Mark Erickson [mailto:[EMAIL PROTECTED] Sent: Sunday, September 18, 2005 11:14 PM To: 'pentax-discuss' Subject: RE: green button wars (again) Actually, Asahi Optical provided limited (not full) compatibility when they switched from their screw mount to the K mount (they abandoned diaphragm coupling and thus lost open aperture metering capability for screw mount lenses on K mount bodies). Regarding your desire for full aperture coupling in Pentax DSLRs, J.C., I basically agree with you. I wish Pentax provided full backward compatibility to M and K lenses, too. That said, I do not find the confrontational gloom-and-doom all-caps approach very motivating. Also, since I am not a camera engineer, I can't comment authoritatively regarding the marginal BOM cost of adding aperture-sensing mechanicals, sensor, electronics, and firmware to an already very small platform. But that's another debate.... --Mark "J. C. O'Connell" <[EMAIL PROTECTED]> wrote: > Cant you guys read my posts before you make such comments about me? I > have explained repeatedly its not just the issue or K/M lenses on an > istD here that concerns me its Pentax turning point decision to no > longer support something without technical or financial CAUSE. Its > ridiculous that a camera as sophisticated as the istD doesn't properly > meter with K/M lenses because of a $5 part's removal for strategic not > photographic or compatability reasons. This situation is ONLY THE > START of something bad because they absolutely had a firm policy for deacdes > to NOT do that kind of thing and now they suddenly have done a 180 > apparently to sell more blades for their razors..
