Pentax DA* 60-250mm f/4 ED [IF] SDM Lens Review

Pentax DA* 60-250mm f/4 ED [IF] SDM Performance

At 60mm, sharpness is already excellent in the centre of the frame at 60mm, with performance towards the edges reaching good levels. Stopping down to f/8 results in excellent sharpness across the frame at this focal length.

Zooming to 135mm and maximum aperture, sharpness drop to good levels in the centre of the frame, with performance towards the edges of the frame falling to fair levels. Clarity in the centre of the frame improves dramatically with stopping down, reaching outstanding levels by f/8, but performance towards the edges of the frame takes longer to catch up, falling just short of excellent sharpness levels at f/11.

Finally, at 250mm, the way this lens performs follows much the pattern at 135mm. At maximum aperture sharpness is good in the centre, but only fair towards the edges of the frame. Sharpness is excellent in the centre between f/8 and f/11 but the lens needs stopping down to f/11 to exceed good levels of clarity towards the edges of the frame.

MTF@60mm

MTF@135mm

MTF@250mm

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 between 60mm and 135mm, going a bit crazy at 250mm. At 250mm fringing approaches 2.5 pixel widths towards the edges of the frame at maximum aperture, which may become visible, especially in images containing areas of high contrast.

CA@60mm

CA@135mm

CA@250mm

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.

Impressively, there is no discernable falloff at 60mm and maximum aperture. At 250mm and f/4, the corners are 0.95 stops darker than the image centre and visually uniform illumination is achieved with the aperture stopped down to f/5.6 or beyond.

Distortion is very well controlled at both ends of the zoom range. Imatest detected 0.7% barrel distortion at 60mm, which is replaced by 0.5% pincushion distortion at 250mm. 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 necessary.

During testing, this lens proved itself very resistant to flare and contrast levels are good, even when shooting into the light. The petal-shaped hood does a decent job of shading the lens from extraneous light that may cause issues.

Value For Money

Being priced at around £1070, this lens is priced roughly in line with similar offerings from other manufacturers for their own camera systems. Due to the unique combination of focal range and a constant f/4 maximum aperture, there aren't currently any other comparable lenses available for Pentax cameras from third party manufacturers.

Add your message