The HD PENTAX-DA 55-300MM F4.5-6.3 ED PLM WR RE gives long telephoto reach from an unusually compact and lightweight package. The effective zoom range gets a 1.5x boost thanks to the APS-C crop factor of Pentax cameras for which it’s designed. This makes it ideal for walkabout and travel photography, as well as for prolonged periods of action, sports and wildlife photography without the need for a tripod.
Mount: Pentax K (APS-C)
Full frame: No
Lens construction: 14 elements in 11 groups
Angle of view: 29-5.4 degrees
Diaphragm blades: 9
Minimum aperture: f/22-32
Minimum focusing distance: 0.93m
Maximum magnification ratio: 0.3x
Filter size: 58mm
Despite being launched around the same time as Pentax’s first full-frame DSLR, this lens is designed exclusively for APS-C format cameras. The required size of the image circle is therefore smaller, and the lens has a slightly slower aperture rating than typical 70-300mm tele zooms for DSLRs, at f/4.5-6.3. These factors enable a smaller and more lightweight build but compactness is further boosted by a crafty design that’s based on a retractable barrel. With a retracted length of just 89mm, it takes up less than two-thirds of the room of most competing lenses for stowage. And whether it’s in use or in your gadget bag, it’s much lighter than most, at just 442g.
The Pentax beats 70-300mm lenses for overall zoom range, enabling a wider viewing angle on APS-C cameras, at their shortest focal length. And while it’s a lightweight in physical terms, there’s no shortage of features and build quality is very good, complete with a full set of weather-seals.
Autofocus is based on a stepping-motor system which is very quick and quiet, although not completely silent. Even so, it’s blissfully quiet compared with many other Pentax lenses. One thing that’s lacking is an optical image stabilizer. Pentax DSLR bodies feature built-in sensor-shift stabilization, but the addition of optical stabilization can give a boost to effectiveness, especially in telephoto lenses. Image quality is very good overall, with impressive contrast and good sharpness throughout most of the zoom range, although it drops off a bit at the long end.
We run a range of lab tests under controlled conditions, using the Imatest Master testing suite. Photos of test charts are taken across the range of apertures and zooms (where available), then analyzed for sharpness, distortion and chromatic aberrations.
We use Imatest SFR (spatial frequency response) charts and analysis software to plot lens resolution at the center of the image frame, corners and mid-point distances, across the range of aperture settings and, with zoom lenses, at four different focal lengths. The tests also measure distortion and color fringing (chromatic aberration).
Peaking at a focal length of 100mm, sharpness drops off slightly at the short end and more noticeably at 200-300mm.
Color fringing is generally quite minimal can be a little noticeable at both ends of the zoom range.
Despite the reduced 55mm focal length compared with 70-300mm lenses, barrel distortion is well controlled at the short end, and there’s only slight pincushion at longer settings.
This lens for Pentax APS-C format DSLRs ticks all the right boxes for photographers who want powerful telephoto reach without getting weighed down in the process. With a retractable design, it shrinks to just 89mm length for convenient stowage and it weighs in at just 442g. That’s despite giving a lengthy 82.5-450mm effective zoom range in full-frame terms, stretching into super-telephoto territory. Build quality, image quality and all-round performance are very good, making the lens very good value at the price.