PENTAX DA* Digital Lenses

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Pro-Quality Lenses For Pentax Digital K-Mount

by Joe Farace

The Zeiss T* (pronounced “Tee-Star”) lenses are legendary for their quality, sharpness and clarity. The new series of DA* digital only lenses from Pentax hope to offer the same kind of optical excellence to users of Pentax and Samsung digital SLRs.

To maximize optical performance, the image circle formed by DA-series lenses is designed to match the 23.5×15.7mm CCD imager used in Pentax digital SLRs. Although neither of the two high-end DA* lenses that I tested could truly be considered “small,” this design approach does produce a reduction in size, weight and cost when compared to 35mm format lenses with similar focal length ranges and maximum apertures. DA* series of lenses use Pentax’s SDM (Supersonic Drive Motor) system that’s quiet and focuses fast because of the higher torque gearless motor used.

 

All DA* series lenses feature a “Quick-Shift Focus System” allowing photographers to rapidly switch focusing modes from autofocus to manual focusing with just a slight twist of the focus ring. When attached on a Pentax’s semi-pro K10D digital SLR, the camera’s focus mode is automatically switched to SDM-assisted autofocusing, but when mounted on other Pentax digital SLRs conventional autofocus mode using the camera-mounted motor is selected. The lenses feature Extra-low Dispersion (ED) glass lens elements for maximum image quality and internal focusing, so the lens doesn’t change size when focusing and the front element of the lens won’t rotate in case you’ve attached a modular filter holder. All the DA* lenses feature a simple functional design that includes eliminating the aperture ring that’s become de rigueur in the modern age of auto-focus SLRs. All this high tech stuff costs money so these are not inexpensive lenses, but you won’t have to stretch your credit card limit to afford them either.

PENTAX DA* 50-135mm f/2.8 ED (IF)

The DA* 50-135mm f/2.8 ED telephoto zoom lens uses three ED (extra-low dispersion) glass elements to minimize chromatic aberrations and produces superb contrast, clarity and edge-to-edge sharpness. The 50-135mm’s lens is tightly sealed and is weather- and dust-resistant to enhance durability when used in rainy or dusty working conditions. The lens features Pentax SP (Super Protect) — didn’t they used to call it Super Multi Coating? — ghostless coating to minimize internal reflections and improves capture of backlit subjects. The coating also repels dust, water and grease, which, if you read my story on caring for your camera in the January 2008 issue Pro Digital Imaging, is a good thing. The DA* 50-135mm f/2.8 ED lens is bundled with a soft protective case and includes a reversible tulip-shaped lens hood. It’s a true pro-quality lens.

PENTAX DA* 16-50mm f/2.8 ED/AL (IF)

Like other DA* series lenses, the 16-50mm f/2.8 wide angle zoom lens incorporates ED (extra-low dispersion) glass elements and three aspherical elements to compensate for chromatic and spherical aberrations—that’s what the “AL” in its name stands for. The lens surface is coated with a special fluorine compound by using a vapor deposition process that’s designed to repel dust, water, grease and makes it easy to wipe off fingerprint smudges. When mounted on a Pentax digital SLR camera body, this 3.1X zoom lens covers the angles of view equivalent to 24.5-76.5mm in the 35mm format making it a seriously useful lens for all-around photography. The lens comes with a soft case and a reversible tulip-shaped lens hood. Be sure to use it!

In the Field

The first thing you’ll notice about Pentax DA* series lenses is that they are solid, well-made and feel good in your hands. The gold striping on the barrel and gold trim accent the high build quality of these lenses. The SDM on both lenses provides quiet and fast autofocus under all kinds of lighting conditions. Zoom action is smooth and for those who like to manually focus there’s a MF>AF control and a real, not wimpy size manual rubberized ring that’s smooth and easy to focus. Similarly, the lens zoom ring is wide and easy to grip and because these are internal focus lenses the barrel does not change size, focuses fast (there’s fewer elements to move) and there’s no focal length drift like I’ve experienced with some zoom lenses from other manufacturers. So neither lens needs a lock control.

Because these lenses are designed for the smaller imaging chip that’s found inside Pentax digital cameras instead of the full (24x36mm) 35mm film frame, they are smaller than they might otherwise be and are well balanced on the different Pentax digital SLRs I tested them with. The lenses performance capabilities is borne out in the crisp, clean image files that were produced when mounted on a K100D Super and should be even more apparent when used with the K10D, which takes advantage of all the special features DA* lenses bring to that camera. Even when shot under low light and the maximum f/2.8 aperture, the captured images were more than acceptably sharp especially on the 16-50mm lens because of it’s aspheric elements.

Together the two lenses provide coverage from 16-135mm (or 24 to 200mm in 35mm terms) and no matter which way you measure them, that’s an exceedingly versatile focal length range. Combined with superb optical performance these two DA* lenses make a perfect pair for travel and all-around photography from portraiture to architecture. When stacked up against expensive lenses from other companies, these lenses are a bargain in terms of solid construction and optical performance.

Pentax DA* 50-135mm f/2.8 ED (IF)

Specifications

  • Lens Mount: KAF2 Mount
  • Lens Construction: 18 elements in 14 groups
  • Angle of View: 1.5 – 11.9 degrees (when used with Pentax digital SLR camera body)
  • Aperture Control: Automatic
  • Minimum Aperture: f/22
  • Number of Diaphragm Blades: Nine
  • Metering System: TTL open-aperture metering
  • Minimum Focusing Distance: 39.3-inches (1.0m)
  • Filter Size: 67mm
  • Maximum Magnification: 0.17X
  • Dimensions: 3.0 x 5.4-inches (76.5mm x 136mm)
  • Weight: 24.2 oz. (685g) without hood, 27.0 oz. (765g) with hood
  • Price: $829.95
  • Pentax DA* 16-50mm f/2.8 ED/AL (IF)

>Specifications

  • Lens Mount: KAF2 Mount
  • Lens Construction: 15 elements in 12 groups
  • Angle of View: 83 – 31.5 degrees (when used with Pentax Digital SLR camera body)
  • Aperture Control: Automatic
  • Minimum Aperture: f/22
  • Number of Diaphragm Blades: Nine
  • Metering System: TTL open-aperture metering
  • Minimum Focusing Distance: 11.8-inches (0.3m)
  • Filter Size: 77mm
  • Maximum Magnification: 0.21X
  • Dimensions: 3.3 x 3.9-inches (84 x 98.5mm)
  • Weight: 19.9 oz. (565g) without hood; 21.2 oz. (600g) with hood
  • Price: $899.95
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  6. Matt Wilkens says:

    Enjoyed your article on the * lenses. It is funny you reference the Zeiss Star lenses at first, as it was Pentax who held the patent on the coating and sold Zeiss the right to use it on their lenses. Pentax originally used the * on their pro lenses like the 85mm 1.4 as well.

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