K-lenses were usually bigger and M-lenses were usually smaller (compared to the equivalent K-series lens). Some K-series are among the best built lenses ever, so if any manufacturing improvements happened, they were to the purpose of saving money.
Furthermore, there's no documented smc difference between K-series and M-series. Pentax claimed that when turning from M-series to A-series, smc was applied to all surfaces (including glass-to-glass ones), while K and M only had smc on glass-to-air surfaces. However, I doubt a standard smc can be of any help on glass-to-glass surfaces, as multicoating is essential when refraction index changes a lot (and must be accorded to that). A smc designed for glass-to-air will be of little help (and possibly will be worse than nothing) if refraction indexes of the two cemented glass elements are close each other (and I guess a glass should be closer to another glass type than to air). And Pentax never claimed smc variations for different needs (although it would not suprise me to discover that they did that without claiming it). Bye, Dario Bonazza ----- Original Message ----- From: "jmb" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Thursday, November 27, 2003 6:05 AM Subject: Re: Any diff smc vs smc-m (aka k vs m) > William, > > According to Peter Spiro web page I just read the difference is > due to superior coating (smc .ne. smc) and improved > manufacturing process. > > K lenses and M lenses function identically. > > > > William Robb > > > > John >
