The Pentax SMC DA Star 60-250mm F4 ED (IF) SDM ($1,999.95 direct)($1,299.94 at Amazon) is the top-end telezoom in the company's D-SLR lens lineup. It's compact when you consider its range, and pairs well with APS-C Pentax cameras like the K-3($1,085.95 at Adorama) in terms of size. It's a lot more expensive and doesn't have the telephoto reach of the Pentax HD DA 55-300mm F4-5.8 ED WR ($449.95), but it captures about twice the light when zoomed all the way in. Our Editors' Choice telezoom, the Sigma 120-300mm F2.8 DG OS HSM($3,395.60 at Amazon), is not available for Pentax cameras at this time, but Sigma does sell the APO 70-200mm F2.8 EX DG OS HSM ($1,399) in the K-mount if you're in need of a similar lens with a maximum f/2.8 aperture.

The lens is on the large size, but not out of line for an optic that covers its field of view. Pentax doesn't make a full-frame camera, so the field of view is like a 90-375mm lens on a 35mm camera. It measures 6.6 by 3.2 inches (HD), weighs 2.3 pounds, and uses 67mm front filters; a petal style, reversible hood is included. It's a lightweight lens when compared with the Sigma 120-300mm, which has a one-stop advantage in light gathering and has a slightly longer reach; that huge lens measures 11.5 by 4.8 inches, weighs 7.5 pounds, and has a giant front element that requires 105mm filters. The Sigma stays the same length regardless of what focal length it's set at; the Pentax lens telescopes out when zoomed.

A tripod collar is included. It's something we recommend using when you're mounting the lens on a tripod or a support like the the excellent Manfrotto 694CX Carbon Fiber 4-Section Monopod, as it provides better balance than using the tripod socket on your camera. There's a small knob on the collar to lock or unlock it, so you can switch form portrait to landscape orientation without any fuss.

The lens can focus on objects as close as 3.6 feet, which only delivers 0.15x magnification, so don't look to it for macro subjects. The focus motor is an SDM design; our test unit was on the loud side for an internal motor, but it's still quieter than a screw-drive system. Like the other optics in the Pentax DA Star lineup, the 60-250mm is weather-sealed. The same is true for most of the company's D-SLR lineup, so you can use the lens in harsh weather without worry. There's no built-in image stabilization, but that's also not a concern for Pentaxians—the company implements shake reduction in the camera body, not the lens.

I used Imatest to check the sharpness of the 60-250mm when paired with the 24-megapixel K-3. At its 60mm focal length the lens scores 2,029 lines per picture height at f/4 on a center-weighted sharpness test. That's higher than the 1,800 lines we use to define a sharp image, but the outer edges of the frame are noticeably soft to the eye (1,079 lines). Stopping down to f/5.6 improves performance all around; the center-weighted score jumps to 2,368 lines, and the edges hit 1,765 lines. At f/8 the lens is tack sharp from edge to edge, managing a 2,358-line center-weighted score with edges that score 1,940 lines. The mid-parts of the frame, between the center and edges, top 1,900 lines at f/4 all the way through f/8; it's only the very outer edges that disappoint at the widest aperture. There's a very modest amount of barrel distortion, about 0.8 percent, but that's barely worth mentioning. If you notice it in the field it's easily rectified with a quick slider adjustment in Lightroom or a similar workflow application.

The lens sharpens up a bit when zoomed to 90mm, and distortion drops to 0.2 percent of the pincushion variety. At f/4 it scores 2,155 lines, with outer edges that hit 1,620 lines. Stopping down to f/5.6 improves the score to average score to 2,401 lines (with edges that top 2,000 lines) and at f/8 the lens hits 2,546 lines, with edges that top 2,200 lines. It's just as impressive at 140mm. At f/4 there the center-weighted score is 2,189 lines (with edges that top 1,800 lines), and it improves at f/5.6 (2,429 lines) and f/8 (2,273 lines), with edges that approach 2,200 lines at both apertures. There's about 0.5 percent pincushion distortion, which again isn't something that's going to be noticeable in most shots.

Limitations in our test studio prevents proper framing of the test chart at 250mm; I simply can't back the camera far enough away in order to get the chart framed and report an accurate score. Some shots in the field show that it's a bit softer at f/4 than at wider focal lengths, and stopping down to f/5.6 improves things all around. I framed shots at both apertures and compared them in Lightroom; textures were a bit smoothed over at f/4, but crisply detailed at f/5.6. The pixel-level crop above was taken from an image shot at 250mm f/5.6; the camera ISO was set at 200 and the shutter speed 1/500-second, so noise and vibration are not likely to impact sharpness.

I did notice some chromatic aberration, in the form of purple color fringing, in high contrast areas of some shots when shooting the lens along with the K-3. It's fairly modest, and easily corrected in Lightroom. That wasn't an issue with the Sigma 120-300mm, and that lens is impeccably sharp through its entire zoom range, from edge-to-edge, at f/2.8—but it's 7.5 pounds and $3,600, so you get what you pay for, and probably some chiropractic bills to go along with that image quality.

But the Sigma isn't available for Pentax shooters, and if you're happy with an APS-C sensor, the extra weight and cost that come with a full-frame telezoom aren't something you should have to deal with. Pentax D-SLR shooters have a solid telezoom in the form of the SMC DA Star 60-250mm F4 ED (IF) SDM, although not a perfect one. A fixed f/2.8 aperture would be welcome for those covering events; if you shoot weddings and the like, the DA Star 50-135mm F2.8 ED (IF) SDM, is likely a better match for your camera. But if you need a longer reach—for wildlife, a visit to the zoo, or the like—the 60-250mm is a solid choice. When working in daylight it won't be a problem to stop it down to f/5.6, you'll still be able to get a relatively shallow depth of field at that aperture when working at longer focal lengths. Even though it sells for less than its retail price, it's still an expensive lens, but the all-weather design will be worth it to many shooters. If that's not important, but a longer telephoto reach at f/2.8 is, the Sigma 70-200mm is a viable alternative with a similar street price.

Pentax SMC DA Star 60-250mm F4 ED (IF) SDM 3.5 See It $1,299.94 at Amazon MSRP $1,999.95 Pros Impressive zoom range and telephoto reach.

Constant f/4 aperture.

Sharp through most of zoom range.

Weather-sealed design.

SDM focus motor. View More Cons Some softness at the edges of the frame and at 250mm f/4.

Some chromatic aberration.

Extends when zoomed.

Pricey. View More The Bottom Line The Pentax SMC DA Star 60-250mm F4 ED (IF) SDM is a weather-sealed telezoom lens that is compact when you consider its range and aperture, but it's not optically perfect.

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