Pentax DA 40 and 70mm lens corner sharpness, tested with Pentax K10D
To measure corner sharpness we photographed
the Enhanced Digital Camera Resolution Chart with each lens using a Pentax K10D. The K10D was set to its best quality JPEG 10M *** mode.
Each lens was tested with various
apertures selected in Aperture Priority mode; the DA 18-55mm was tested at both 18 and 55mm focal lengths. The crops are taken from the lower
left corner of the chart and presented here at 100%.
In these tests of a chart photographed at fairly close range, neither the Pentax 40 nor 70mm lenses can be described as pin-sharp in the corners at wider apertures, but they're both much more impressive than the DA 18-55mm kit lens at 18mm - and their f2.8 and f2.4 maximum apertures are brighter than the f3.5 of the kit lens. The fairer comparison in terms of focal length though is with the kit lens zoomed-into 55mm. While its maximum aperture is only f5.6 at this focal length, it still performs impressively in the corners even with the aperture wide open. It's certainly one of the better kit lenses in this respect.
