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What is HD Coating?


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.

 
Comparison of the reflectance of multi-layer coatings

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.

 
Unevenness of reflectance with
conventional multi-layer coatings

Unevenness in reflectance of HD Coating

 

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 technologyA 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.

Comparison of unevenness in layer thickness

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.

Comparison of reflectance by lens coating

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.

HD PENTAX-FA 35mmF2Versatile 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?

 
Comparison of reflectance on lens surface of the FA 35mm F2 lens

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

smc PENTAX-FA35mmF2 AL
HD PENTAX-FA35mmF2
 

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.

Comparison of transmissivity and Lens Construction

Comparison of transmissivity
Lens Construction

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.

Renewed designAn 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) CoatingFluorine 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

Find more information on Product Page

 

 

『HD PENTAX』Lens lineup

Category Type Lens Product Name Focal Length

w / FF *
w / APS-C *

Aperture
Wide-Angle Lenses Zoom HD PENTAX-DA FISH-EYE10-17mmF3.5-4.5ED
NEW!APS-C
10-17mm
-
F3.5-4.5
HD PENTAX-DA11-18mmF2.8ED DC AW
APS-C
11-18mm
17-27.5mm
F2.8-22
HD PENTAX-D FA 15-30mmF2.8ED SDM WR
35mm Full FrameAPS-C
15-30mm
23-46mm
F2.8
Single Focus HD PENTAX-FA35mmF2
35mm Full FrameAPS-C
35mm
53.5mm
F2
HD PENTAX-DA 15mm F4ED AL Limited
APS-C
15mm
23mm
F4
HD PENTAX-DA 21mm F3.2AL Limited
APS-C
21mm
32mm
F3.2
Standard Lenses Zoom HD PENTAX-DA 16-85mm F3.5-5.6ED DC WR
APS-C
16-85mm
24.5-130mm
F3.5-5.6
HD PENTAX-DA 18-50mm F4-5.6 DC WR RE
APS-C
18-50mm
27.5-76.5mm
F4-5.6
HD PENTAX-DA 20-40mm F2.8-4ED Limited DC WR
APS-C
20-40mm
30.5-61.5mm
F2.8-4
HD PENTAX-D FA 24-70mmF2.8ED SDM WR
35mm Full FrameAPS-C
24-70mm
37-107mm
F2.8
HD PENTAX-D FA 28-105mmF3.5-5.6ED DC WR
35mm Full FrameAPS-C
28-105mm
43-161mm
F3.5-5.6
Single Focus HD PENTAX-DA 40mm F2.8 Limited
APS-C
40mm
61mm
F2.8
HD PENTAX-D FA50mmF1.4 SDM AW
35mm Full FrameAPS-C
50mm
76.5mm
F1.4
Telephoto Lenses Zoom HD PENTAX-DA 55-300mm F4-5.8ED WR
APS-C
55-300mm
84.5-460mm
F4-5.8
HD PENTAX-DA 55-300mmF4.5-6.3ED PLM WR RE
APS-C
55-300mm
84.5-460mm
F4.5-6.3
HD PENTAX-D FA70-200mm F2.8ED DC AW
35mm Full FrameAPS-C
70-200mm
107-307mm
F2.8
HD PENTAX-D FA 150-450mm F4.5-5.6ED DC AW
35mm Full FrameAPS-C
150-450mm
230-690mm
F4.5-5.6
Single Focus HD PENTAX-DA 70mm F2.4 Limited
APS-C
70mm
107mm
F2.4
HD PENTAX-DA 560mm F5.6ED AW
APS-C
560mm
859mm
F5.6
Macro Lenses Single Focus HD PENTAX-DA 35mm F2.8 Macro Limited
APS-C
35mm
53.5mm
F2.8
Converter / AF Lens Adapter HD PENTAX-DA AF REAR CONVERTER 1.4X AW - -

HD PENTAX-DA FISH-EYE10-17mmF3.5-4.5EDA versatile fish-eye zoom lens, featuring HD Coating and a removable lens hood to assure a greater range of creative expression

 

Based on the smc PENTAX-DA FISH-EYE 10-17mm F3.5-4.5ED[IF], which provided a maximum angle of view of 180 degrees and a distinctive image rendition, this fish-eye zoom lens is designed to deliver sharp, clear images with minimal flare and ghost images against backlight, thanks to a thorough review of all lens coatings and the application of high-grade, multi-layer HD Coating.

This lens features a new exterior design matching those of PENTAX K-series digital SLR cameras and the latest interchangeable lenses, and a removable lens hood. When mounted on a 35mm full-frame PENTAX K-series digital SLR camera, it lets you enjoy eye-catching fish-eye photography with a nearly circular image circle.

The Origin of Fish-eye Zoom Lenses

People often associate fish-eye zoom lenses with zoom lens versions of conventional fish-eye lenses.

Going back in history to the film-photography era, when zoom lenses were first invented, only zoom lenses with a very expansive angle of view were ultra-wide-angle zoom lenses. Since these ultra-wide-angle zoom lenses required compensation for distortions over the entire zoom range, optical designers had to supply a sufficient amount of light to the edges of the image field. The result was that most of these lenses were too heavy and cumbersome to simply carry around, and their use was limited only to scenic and architectural photography.

Then came the smc PENTAX-F Fish-Eye Zoom 17-28mm F3.5-4.5 — PENTAX’s first-generation fish-eye zoom lens, and the world’s first of its kind. It was developed from a single idea proposed by the PENTAX engineering team: convert an ultra-wide-angle zoom lens into a fish-eye zoom lens.

Achieving this goal would give PENTAX three advantages in lens design:

1. A wide-angle lens has a retro-focus design, in which a concave optical element is positioned at the front. However, this design tends to cause barrel distortion. In order to compensate for this distortion, a number of additional optical elements are required, making the final product quite large and heavy. A fish-eye lens, however, doesn’t require extensive compensation because it can use this distortion to its advantage and produce unique, eye-catching images. As the result, the number of optical elements can be considerably reduced.

2. A conventional wide-angle lens has a short focal length in order to broaden its angle of view and increase the retro-focus effect, which enlarges the lens body. But a fish-eye lens can create a vast angle of view using its distortion. The result is that the unnecessary shortening of the focal length is eliminated.

3. Because distortion causes a compression effect on surrounding areas, a fish-eye lens can prevent the reduction of light level in peripheral areas, a concern with an ultra-wide-angle lens. Therefore, a fish-eye lens doesn’t require a large optical element at the front.

By applying a fish-eye optical design to a large, cumbersome ultra-wide-angle zoom lens, PENTAX successfully developed a fish-eye zoom lens which was more compact, lighter in weight and much easier to handle.

〔smc PENTAX-F Fish-Eye zoom 17-28mmF3.5-4.5〕

Developing a Fish-eye Zoom Lens with a Shorter Focusing Distance

The first-generation fish-eye zoom lens — the smc PENTAX-F Fish-eye Zoom 17-28mm F3.5-4.5 — left one problem to be solved: its minimum focusing distance of 0.45 meters made it difficult to close in on the subject. Since it used a front-group-extension focusing mechanism, the zoom effect during focusing operation made the angle of view wider, resulting in vignetting in close-up photography.

In the development of the smc PENTAX-DA FISH-EYE 10-17mm F3.5-4.5ED[IF], which was designed for use with APS-C-format digital SLR cameras, PENTAX aimed at shortening the minimum focusing distance — one objective left unsolved with the first-generation fish-eye zoom lens — and adopted the Inner Focus (IF) mechanism, in which the rear group of the first optical element group was shifted during focusing. This IF mechanism realized an optical system free of vignetting during close-up photography.

With a minimum focusing distance of a mere 0.14 meters, and a minimum distance of 2.5cm between the subject and the front surface of the lens, this new fish-eye zoom lens has greatly expanded the range of photographic applications.

The ability to approach the subject more closely, however, created new problems, such as dirt and scratches on the lens surface caused by the contact with the subject. To solve these, PENTAX developed a new fluorine coating to protect the lens surface. Named SP (Super Protect) Coating, it is not only repellent to water and grease and prevents dust, water drops and oil stains from adhering to the lens surface, but also makes it easy to wipe them off. First applied to the smc PENTAX-DA FISH-EYE 10-17mm F3.5-4.5ED[IF], SP Coating is also featured in the newest HD PENTAX-DA FISH-EYE 10-17mm F3.5-4.5ED.

Grease- and dirt-repellent effect of SP Coating
smc PENTAX-DA FISH-EYE 10-17mm F3.5-4.5ED[IF]

Remarkable Optical Performance Made Possible by HD Coating

Thanks to the application of HD Coating, the HD PENTAX-DA FISH-EYE 10-17mm F3.5-4.5ED not only delivers clearer, sharper images than its predecessor, but also assures higher imaging performance against backlight.

〔smc PENTAX-DA FISH-EYE10-17mmF3.5-4.5ED[IF]〕

 

〔HD PENTAX-DA FISH-EYE10-17mmF3.5-4.5ED〕

A’: Higher contrast due to reduced flare


 

B’: Reduced ghost images
C’: Higher contrast due to reduced flare

New Exterior Design and Removable Lens Hood

The exterior features a wrinkle-finished surface, with meticulous attention paid to every detail. This totally redesigned body makes it a perfect match with the latest camera bodies and other lenses.

With previous models, the lens hood was integrated into the lens barrel. With the HD PENTAX-DA FISH-EYE 10-17mm F3.5-4.5ED, however, it is designed to be removable to provide greater options in photographic expression.

When mounted on PENTAX KP

 

When mounted on PENTAX K-1 Mark II (without lens hood)

This lens provides fish-eye photography with a nearly circular image circle, when mounted on one of 35mm full-frame digital SLR camera bodies in the PENTAX K-1 series. (This image was captured in the FF setting of the Crop mode, without the lens hood. Since this image contains objects outside the image circle, it may suffer reduced imaging performance and/or vignetting in peripheral areas.)

『HD PENTAX』Lens lineup

Category Type Lens Product Name Focal Length

w / FF *
w / APS-C *

Aperture
Wide-Angle Lenses Zoom HD PENTAX-DA FISH-EYE10-17mmF3.5-4.5ED
NEW!APS-C
10-17mm
-
F3.5-4.5
HD PENTAX-DA11-18mmF2.8ED DC AW
APS-C
11-18mm
17-27.5mm
F2.8-22
HD PENTAX-D FA 15-30mmF2.8ED SDM WR
35mm Full FrameAPS-C
15-30mm
23-46mm
F2.8
Single Focus HD PENTAX-FA35mmF2
35mm Full FrameAPS-C
35mm
53.5mm
F2
HD PENTAX-DA 15mm F4ED AL Limited
APS-C
15mm
23mm
F4
HD PENTAX-DA 21mm F3.2AL Limited
APS-C
21mm
32mm
F3.2
Standard Lenses Zoom HD PENTAX-DA 16-85mm F3.5-5.6ED DC WR
APS-C
16-85mm
24.5-130mm
F3.5-5.6
HD PENTAX-DA 18-50mm F4-5.6 DC WR RE
APS-C
18-50mm
27.5-76.5mm
F4-5.6
HD PENTAX-DA 20-40mm F2.8-4ED Limited DC WR
APS-C
20-40mm
30.5-61.5mm
F2.8-4
HD PENTAX-D FA 24-70mmF2.8ED SDM WR
35mm Full FrameAPS-C
24-70mm
37-107mm
F2.8
HD PENTAX-D FA 28-105mmF3.5-5.6ED DC WR
35mm Full FrameAPS-C
28-105mm
43-161mm
F3.5-5.6
Single Focus HD PENTAX-DA 40mm F2.8 Limited
APS-C
40mm
61mm
F2.8
HD PENTAX-D FA50mmF1.4 SDM AW
35mm Full FrameAPS-C
50mm
76.5mm
F1.4
Telephoto Lenses Zoom HD PENTAX-DA 55-300mm F4-5.8ED WR
APS-C
55-300mm
84.5-460mm
F4-5.8
HD PENTAX-DA 55-300mmF4.5-6.3ED PLM WR RE
APS-C
55-300mm
84.5-460mm
F4.5-6.3
HD PENTAX-D FA70-200mm F2.8ED DC AW
35mm Full FrameAPS-C
70-200mm
107-307mm
F2.8
HD PENTAX-D FA 150-450mm F4.5-5.6ED DC AW
35mm Full FrameAPS-C
150-450mm
230-690mm
F4.5-5.6
Single Focus HD PENTAX-DA 70mm F2.4 Limited
APS-C
70mm
107mm
F2.4
HD PENTAX-DA 560mm F5.6ED AW
APS-C
560mm
859mm
F5.6
Macro Lenses Single Focus HD PENTAX-DA 35mm F2.8 Macro Limited
APS-C
35mm
53.5mm
F2.8
Converter / AF Lens Adapter HD PENTAX-DA AF REAR CONVERTER 1.4X AW - -

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