John, There is no difference in function between K and SMC-M lenses. The M lenses are generally lighter and smaller sized than the K's and usually have a 49mm front filter size.
The K's are very similar to the SMC screwmount line of lenses that they replaced in terms of size and weight. The M's go along with the 2nd generation of K-mount cameras that Pentax produced, the smaller and lighter ME and MX cameras. Along with the ME Super, these were some of the most widely produced and used 35mm cameras of all time. (Like in the watch industry, the introduction of electronic chips enabled the creation of precision instruments at a substantial reduction in costs.) Regards, Bob S. [EMAIL PROTECTED] writes: > Do the K mount lenses with just SMC function > differently then the SMC-M lenses? >
