For sharpness testing, we used an Edmund Resolution Power Chart and field tests. Since the Pentax 50mm are considered short telephoto on the K5, it was necessary to place the chart 5 feet from the camera. Once the chart filled the viewfinder, a series of pictures were taken at various apertures. The use of a standard test chart allows the viewer to compare different lenses subjectively.
For the field sharpness testing, we selected an interesting building. We then cropped the picture to include an area with sufficient features that allow for a detailed examination.
Surprising, the winner for the image quality test was a draw. The initial results of the lens test chart indicated that the Pentax D FA 50mm F2.8 Macro was the better lens. It would have been very surprising if the macro lens did poorly on this test since it is designed to photograph flat objects. But once the Pentax DA and FA 50mm were stopped down beyond F4 they performed as well as the macro. The outside field test results were very similar. The Pentax DA 50mm started out better than the FA 50mm wide open but that advantage did not continue. Once you compare the shots taken with the Pentax D FA 50mm macro at F2.8 and above the results of the DA and FA 50mm are so similar that if the pictures weren’t labeled we probably could not tell the difference between the lenses. Overall the results were about the same. It was interesting that depending on the F stop, a particular lens would excel.