The Pentax HD DA 70mm F2.4 Limited ($749.95 direct) is a compact, short telephoto lens that’s compatible with Pentax D-SLRs. It covers an APS-C image circle, capturing roughly the same field of view as a 105mm lens on a full-frame camera. It’s part of the company’s Limited lens series, and as such boasts a sturdy all-metal construction, as well as a compact design. Here we see some sacrifice in light gathering capability, especially when compared with the Pentax SMC-P FA 77mm F1.8 Limited ($1,049.95), a full-frame lens that remains in production.
The 70mm F2.4 measures just 1 by 2.5 inches (HD) and weighs 4.6 ounces. It is identical in size and shape to the older SMC DA 70mm F2.4 Limited, which is available for less money if you can still find it in stock, but adds the improved HD lens coating and rounded aperture blades. The 70mm focuses to 2.3 feet, netting just 0.12x magnification, so look elsewhere if you’re interested in a macro lens. It includes a screw-in, telescoping metal hood and a push-on lens cap. You’ll have to remove the hood to use filters; the lens uses a standard 49mm thread. The maximum f/2.4 aperture is capable of capturing images with a shallow depth of field, even on an APS-C image sensor, but serious portrait shooters may want to opt for the 77mm f/1.8 lens, as its slightly longer focal length and wider aperture are capable of capturing an even shallower depth of field. Unlike most Pentax D-SLRs, and some lenses like the HD DA 20-40mm F2.8-4 ED Limited DC WR, the 70mm Limited is not weather sealed.
I used Imatest to check the sharpness and distortion characteristics of the lens when paired with the 24-megapixel K-3. We consider an image to be sharp if it scores 1,800 lines per picture height using a center-weighted methodology. The 70mm notches 2,003 lines at f/2.4 with just a little bit of softness at the very edges of the frame. Narrowing the aperture to f/4 improves that figure to 2,319 lines, crisp from edge to edge, and the lens is at its best at f/5.6 where it records 2,396 lines. Distortion is a nonissue; the 70mm only shows about a half percent, which is irrelevant in field conditions.
The Pentax HD DA 70mm F2.4 Limited is an impressive lens. It’s well built, compact, and very sharp, even at its maximum aperture. There’s a little softness at the edges at f/2.4, but that’s a nonissue if you’re using it for shallow depth of field portraiture, and by the time you get to f/4 the lens is tack sharp from edge to edge. The worst thing you can say about it is that it’s not the FA 77mm Limited. That lens is legendary in the Pentax world; it’s built to the same standards as the DA 70mm, and is capable of capturing even more light and a shallower depth of field when desired. The 77mm is more expensive, but it offers compatibility with full-frame cameras and it’s got a very special look to it that lab tests can’t capture. The DA 70mm is no slouch, and if you value its compact size and are happy with an f/2.4 optic it’s an excellent one, but give careful consideration to the 77mm Limited if you can stretch your budget a bit further.
|Dimensions||1 x 2.5 inches|
|35-mm Equivalent (Wide)||105 mm|
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