HD Pentax-DA 55-300mm f/4-5.8 ED WR Lens Review

HD Pentax-DA 55-300mm f/4-5.8 ED WR Performance

At 55mm and maximum aperture, sharpness is outstanding in the centre of the frame and approaches excellent levels towards the edges of the frame. Stopping down to between f/5.6 and f/11 produces excellent sharpness across the frame at this focal length.

Zooming to 100mm results in similar sharpness in the centre of the frame at maximum aperture, although clarity towards the edges of the frame is noticeably reduced. Here clarity is still outstanding in the centre, but falls just short of good sharpness towards the edges of the frame. Stopping down to between f/8 and f/11 results in peak sharpness across the frame at this focal length.

Finally, at 300mm, sharpness is very good in the centre of the frame at f/5.8 and remains so when stopped down. Unfortunately, clarity towards the edges of the frame drops just below fair levels at maximum aperture. Stopping down improves performance towards the edges of the frame slightly, although it never really achieves good levels of performance here.

MTF@55mm

MTF@100mm

MTF@300mm

How to read our charts The blue column represents readings from the centre of the picture frame at the various apertures and the green is from the edges. Averaging them out gives the red weighted column. The scale on the left side is an indication of actual image resolution. The taller the column, the better the lens performance. Simple. For this review, the lens was tested on a Pentax K-5 IIs using Imatest.

Chromatic aberrations are well controlled for much of the zoom range, barely exceeding three quarters of a pixel width towards the edges of the frame for much of the zoom range. However, it's a different story at 300mm, where ringing exceeds one pixel width at maximum aperture. This level of fringing may be possible to spot, especially in harsh crops from the edges of the frame along high contrast details.

CA@55mm

CA@100mm

CA@300mm

How to read our charts Chromatic aberration is the lens' inability to focus on the sensor or film all colours of visible light at the same point. Severe chromatic aberration gives a noticeable fringing or a halo effect around sharp edges within the picture. It can be cured in software. Apochromatic lenses have special lens elements (aspheric, extra-low dispersion etc) to minimize the problem, hence they usually cost more. For this review, the lens was tested on a Pentax K-5 IIs using Imatest.

Falloff of illumination is well controlled for a telephoto zoom. At 55mm the corners of the frame are 0.76 stops darker than the image centre and at 300mm the corners are 0.98 stops darker. Visually uniform illumination is achieved with the lens stopped down by one full stop from maximum aperture throughout the zoom range.

Distortion is also well controlled for a lens of this type. Imatest could only detect 0.05% barrel distortion at 55mm and 1.27% pincushion distortion at 300mm. The distortion pattern is uniform across the frame, which should make it relatively easy to apply corrections in image editing software afterwards if absolutely straight lines are paramount.

During testing, this lens proved itself very resistant to flare and contrast is retained well, even when shooting into the light. The deep circular hood does an excellent job of shading the lens from extraneous light that may cause issues with flare.

Add your message