Pentax HD DA 40mm f2.8 Limited lens review: Compelling choiceBy Kevin Carter - Thursday January 02 2014 Lens Review
Pentax HD DA 40mm F2.8 Limited Versus Pentax smc DA 40mm f2.8 XS Versus Pentax smc DA 40mm F2.8 Limited all three mounted on Pentax K-50
Although the XS version is based on a similar design to the Limited models, it has slightly better transmission than the new HD model but it has much higher levels of chromatic aberration than either. In terms of sharpness, the HD and XS models perform similarly at the initial aperture – with only moderate sharpness, whereas the older smc Limited model has slightly lower sharpness still. At f4 the new HD model is slightly sharper in the center but from f5.6 onwards they have similar sharpness.
Pentax HD DA 40mm F2.8 Limited mounted on Pentax K-50 Versus Canon EF 40mm f/2.8 STM mounted on Canon EOS 100D:
We were interested to compare the 40mm lens with the new EF 40mm f2.8 STM from Canon. Keep in mind that although the two are the equivalent to a 60mm on APS-C cameras, the Canon is in fact a full frame lens and the results on the Canon EOS 100D used for testing reflect a crop from the center. Unsurprisingly perhaps, the Canon exhibits slightly less distortion and vignetting than the Pentax but it has very high levels of lateral chromatic aberration by comparison.
As for sharpness, the Canon is slightly sharper at full-aperture and it has reasonable corner sharpness albeit not particularly uniform across the field. The Canon is also slightly sharper across the field when stopped down with peak sharpness of 10P-Mpix at f5.6 – a slightly better performer in terms of uniformity.