Super Multi Coating by Pentax — multi-layer lens coating that reduces reflections and flare for cleaner, higher-contrast images.
Technical Details
SMC coatings work on the principle of destructive interference, with each layer optimized for specific wavelengths between 400-700nm. Modern SMC systems achieve transmission values of 99.8% per element compared to 96% for uncoated lenses. For an 8-element lens, total transmission increases from 72% to 98.4%. The coating is applied in a high vacuum by evaporation or ion beam sputtering at temperatures around 300°C. Special variants like SMC-NCS (Nano Crystal Coating) integrate nanostructured surfaces for even lower reflections.
History & Development
Pentax introduced SMC coating in 1975, after Zeiss had already developed the first single-layer coating in 1935. Canon followed in 1987 with Super Spectra Coating, and Nikon in 1988 with Super Integrated Coating. The crucial further development came in 2005 with nanostructured coatings, which further reduced reflections by 50% at critical angles. Since 2010, computer-aided design methods have enabled optimization for specific spectral ranges of digital sensors.
Practical Use in Film
For "Blade Runner 2049," DoP Roger Deakins used SMC-coated vintage lenses to avoid ghosting despite complex lighting. The coating allows for the use of strong backlight scenes without disturbing lens flares. In Steadicam work, SMC coating reduces flares during rapid pans through changing light sources. Disadvantages arise when lens flares are intentionally desired – in such cases, DoPs must resort to older, less-coated lenses or use filters.
Comparison & Alternatives
SMC coating significantly surpasses simple MC coating (4-7 layers) in flare suppression but does not achieve the perfection of modern nano-coatings like Zeiss T* or Canon's ASC (Air Sphere Coating). Uncoated lenses produce approximately 28% light loss with 8 elements, compared to 1.6% with SMC coating. PVD (Physical Vapor Deposition) coatings offer higher durability, while sol-gel processes are more cost-effective. The choice depends on the desired look: documentaries favor maximum coating, while feature films often deliberately opt for weaker systems for characteristic flares.