[PeterChris]

This has probably been asked before, but I have three Pentax lenses that I bought in the 1980s: SMC Pentax-A 50mm, SMC Pentax-A 35mm, and SMC Pentax-M 135mm. The A is automatic, the M is manual, but what does the SMC mean???

Peter

[paulh]

Super Multi-Coated

[Julie]

According to Pentax K-Mount Lenses Explained: The differences between various Pentax lens series ,

""smc" stands for Super Multi Coating, Pentax's multi-layer lens coating which does a great job of reducing flare. DA, D FA, and some FA lenses have an improved "ghost less" coating that is even more effective than the original coating. Furthermore, there are reasons to believe that the SMC coating has been improved from series to series."

[Na Horuk]

Yep, SMC is the coating. It is a Pentax secret recipe, which was quite special when it first came out. Back then not all lens manufacturers had good multi coating (or even any?). Nowadays most lenses have some type of MC and Pentax's coating is no longer as "outstanding" by comparison. There are rumours that Pentax will now use "HD" coating on their future lenses, so the "SMC" label might no longer be put on lenses. Too bad. (thought the quality of the coatings has been increasing and is only getting better, especially on high-end lenses)

Coatings are put on a lens to improve its resistance, make it easier for cleaning, and also significantly improve its optical qualities.

[tim60]

Any surface in an optical system results in reflection, and the greater the difference in the refractive index the greater the reflections will be. Difference in refractive index of the glass and air is what makes lenses work, directing light as designed.

Originally the coating technology could manage a single coating which gradated the change in refractive index at the element surface, reducing reflections, which are the cause of flare effects.

Then came the idea and technology of multi-coating which placed a series of layers of with small changes of refractive index between each layer. This increases the number of layers at which effects can arise, but greatly reduces the problems at each surface. The performance of the coatings is wavelength dependant, becaseu each coating has some thickness and therefore enables interference of waves which results in wavelength dependant effects.

Pentax introduced SMC about 1972. By the late 70s 'multi-coating' was well known, and the explanation above was what I got in high school physics. I went to a school where cameras were a meaningful illustration for the class. As with all things new discoveries of coating materials and production methods have enabled improvement to the designs.

Australia 3 out for 258 in the first innings in reply to 156 all out at the Boxing Day test.

[jatrax]

so the "SMC" label might no longer be put on lenses. Too bad.

Definitely too bad. I always wonder how the marketing gurus come up with these ideas. They have a legendary product brand "SMC" that is known for quality for years and years. So they change it to 'HD'. What does that mean? SMC has changed numerous times over the years and gotten better but the name did not change. Anyone picking up an older Pentax lens just looked for the SMC designation to know it had the good coating. Why change to something else? Silly.

If the new coating is so much better why not 'SMC II' or 'SMC HD'? Now they have to start from scratch to build brand awareness. Double silly.

[noblepa]

This has probably been asked before, but I have three Pentax lenses that I bought in the 1980s: SMC Pentax-A 50mm, SMC Pentax-A 35mm, and SMC Pentax-M 135mm. The A is automatic, the M is manual, but what does the SMC mean???

Peter

Others have covered the SMC question, so I won't add anything.

The M in the M lenses does not stand for "Manual", although they are manual lenses. After the first generation of Pentax k-mount cameras and lenses was introduced in 1975, Olympus brought out their OM-series cameras, which were much smaller than the typical SLRs of the time. Pentax responded with the M-series of cameras, including the ME, ME Super, MX, MG, MV1, and so on. These were also much smaller cameras than previous Pentaxes. The M-series lenses were physically smaller than the previous K-mount lenses. In many cases, the M-series lenses were optically identical to their K-series counterparts, but not always.

The A series lenses were introduced next, along with cameras such as the Super Program, A3000, P3, P5. These lenses and cameras now had electrical contacts in the lens mount, that allowed the camera and lens to communicate more information back and forth. Specifically, it allowed the camera to control the aperture automatically. These were the first cameras to have Aperture Priority exposure mode.

[PeterChris]

Interesting! None of this in the owner's manual that came with my camera, a Program Plus. So thank you!

Peter