HD Coating is a new-generation, multi-layer lens-coating technology, developed to provide better-quality optical characteristics in a greater number of lens products. It was designed to satisfy the demand for higher lens performance that is required by advances in digital cameras.
With the application of a state-of-the-art multi-coating process completely different from the conventional one, HD Coating provides a coating layer thickness and anti-reflection performance that is close to theoretical design specifications. A lens surface treated with HD Coating assures reflectance that is less than 50% that of conventional multi-layer coatings.
The graphs above show the optical performance of samples selected from each category, after treatment with 10 layer-forming processes. As you can see, HD Coating samples show extremely high layer-forming precision and extremely low discrepancy in reflectance. Since reflectance curves are almost identical at different wavelengths, the HD Coating graph demonstrates optical characteristics which deliver ideal color balance.
The history of PENTAX lens coating technology
A pioneer of multi-layer lens coating technology
In 1971, PENTAX made an innovative advancement in optical technology by increasing the number of coating layers from two — the norm at the time — to as many as seven.
Since then, lenses with the prefix “smc PENTAX” have been preferred by many photo enthusiasts. With the advancement of production technologies and camera digitalization, PENTAX’s multi-layer coating technology has continued to evolve to meet the demands of the times.
Development of Aero Bright Coating boasting the highest anti-reflection performance
PENTAX later developed Aero Bright Coating, which provided excellent transmissivity through a wider range of wavelengths and outstanding anti-reflection performance, by applying a silica aerogel coating layer with a uniform porous structure over a regular multi-coating.
Aero Bright Coating was first introduced in 2009 to the smc PENTAX-DA★ 55mm F1.4 SDM, and helped to further improve the optical characteristics of high-performance lenses.
The birth of higher-performance, more cost-efficient HD Coating
Even though Aero Bright Coating had superior anti-reflection performance, its nano-order, porous structure has a very delicate coating structure that can be easily damaged by abrasions or scratches. Because of this, its application was limited to a small selection of lens surfaces. It also wasn’t suited for mass production because of restrictions faced in the production process. It therefore could be applied only to rather high-priced models.
To resolve this setback, PENTAX set out to further upgrade its multi-layer coating technology — something indispensable in optical glass — and achieve an optical performance close to that of Aero Bright Coating. Compared with a conventional seven-layer coating applied by a vacuum evaporation process, the new HD Coating forms an eight-layer coating with a uniform layer thickness, created by a high-precision, ion-assisted evaporation process. This is further reinforced by a ninth coating added to the outermost layer by a vacuum evaporation process.
The graph above demonstrates the unevenness in coating layer thickness generated by different coating processes. The ion-assisted evaporation process used for HD Coating has a larger number of samples with zero deviation than the vacuum evaporation process. It also shows a smaller deviation from average thickness.
Because this new coating process minimizes the unevenness in layer thickness created during the coating process, it can improve the overall optical performance of nine-layer HD Coating. Thanks to a higher packing density, it also forms an extremely solid coating layer, making it possible not only to improve lens quality, but also to enhance its applicability across a wider range of lens surfaces and imaging products.
HD Coating demonstrates exceptional anti-reflection performance, far superior to that of the conventional multi-layer coating but also close to Aero Bright Coating — PENTAX’s top-grade lens coating — in the visible ray range (400 to 700 nanometers).
PENTAX intends to expand the HD PENTAX-series lens lineup featuring high-performance, cost-efficient HD Coating.
Versatile wide-angle lens compatible with 35mm full-frame format, remodeled with the latest lens coating
Since its launch as a lens for use with 35mm film-format SLR cameras, the smc PENTAX-FA 35mm F2AL has become a long-selling, multi-application wide-angle lens because of its exceptional resolving power, even after cameras became digital.
In recent years, large, the number of heavy, high-performance lenses is on the increase to accommodate higher-resolution digital cameras. The HD PENTAX-FA 35mm F2, however, retains the well-conceived optical design and compact dimensions of its base model, while also being remodeled to deliver higher performance through a complete review of the entire lens coating process.
By applying the latest, high-performance multi-layer HD Coating, the lens delivers a high-resolution, high-contrast image that is sharp and clear even at the edges.
What are the benefits of HD Coating?
The graph above demonstrates the reflectance of the old and new FA 35mm F2 lenses on the identical lens surface. The HD PENTAX-FA 35mm F2 assures a better anti-reflection performance over the visible ray range (400 to 700 nanometers).
Comparison of anti-backlight performance
Even under adverse conditions such as a strong light source in the image field, HD Coating effectively reduces the generation of ghost images, compared to conventional multi-layer coatings.
Although both the old and new FA 35mm F2 lenses feature a simple lens construction, the HD PENTAX-FA 35mm F2 assures higher transmissivity as a whole, because its HD Coating-treated lens surfaces have superior anti-reflectance performance.
Born in 1969 in Hyogo Prefecture. After graduating from the Nippon Photography Institute, Sasaki worked in rental studios and as a professional’s assistant before going independent. Currently he calls himself a “street photographer,” and works to create images while writing for magazines. In the film era, he specialized in monochrome photographer, only turning to work in color photography when he ventured into the digital realm. He strongly believes in making originals only in print. （http://www.facebook.com/KeitaPage2）
“I traveled to Kamakura and Hokkaido carrying a new HD PENTAX-FA 35mmF2 treated with HD Coating. Carrying just one single-focus lens forced me to experiment with various techniques. This approach also encouraged me to learn more about the destinations.
“A full-frame 35mm lens is commonly considered a wide-angle lens, but I personally regard it as a standard lens with a slightly wider perspective. Its compact dimensions and versatile angle of view allow me to easily react to any unexpected encounter on the road. It also lets me move in a little closer to the subject. These factors made me decide that this was a perfect lens for traveling.
“To tell you the truth, I had never used the smc PENTAX-FA 35mm F2 before, so I cannot make accurate comparison of lens performance, such as the effects of lens coating especially against backlight. However, I felt comfortable with this new lens because it assured easy exposure control with rich, true-to-life description of gradation and texture in dark areas, especially against backlighting and diagonal lighting in which contrast tends to become stronger.
“I think that the benefits of lens coating are easier to compare digitally in terms of numerical values, but I honestly welcomed this upgrade because it provides me with a sense of comfort and security.”
An exterior design matching the current lens lineup, and in harmony with digital SLR camera bodies
The lens exterior is treated with a wrinkle finish identical to that of camera bodies and other lenses. The lens also features a Green Ring as a design element.
SP (Super Protect) Coating
Fluorine coating for easy maintenance
PENTAX treats the front surface of the first optical element of many lenses with SP Coating, a high-strength fluorine coating which effectively protects the lens. Highly repellent to water and grease, it not only prevents adhesion of dust, water drops and oils, but also makes it easy to wipe off such objects from the lens surface.
35mm full-frame wide-angle lens featuring advanced technology and easy handling in a compact body HD PENTAX-FA 35mmF2