I wrote: > 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.
I was wrong. The claim of applying SMC on all surfaces, including glass-to-glass, was made on occasion of launching the SMC Pentax lens line (as as opposed to SMC Takumars, which only had SMC on glass-to-air surfaces). Sorry for this mistake, and thanks to Andre for reminding me how things were going. > 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). Above comments remain valid, and are more on topic of this K/M discussion. I have to add that during the years SMC was changed, as you can spot different color reflections on lenses (even on lenses of the same type, not only comparing different lenses). Asahi never documented such changes in coating quality, but they occurred. It is generally believed that A-series lenses usually feature improved contrast over their M-series counterparts. Dario Bonazza www.aohc.it
