I´m tired of all of this talk about sharpness. What about vignetting and distortion. The latter is the reason why i´m not very happy with my A20mm.
DagT Den 18. jul. 2006 kl. 18.49 skrev Joseph Tainter: > My DA 21 F3.2 Limited arrived yesterday, so last evening I went out to > test it against the FA 20 F2.8. I followed my usual protocol: > > Subject was a mud-brick wall, with cracks and many small rocks. > Tripod. > Distance for the DA 21 was about 1 meter. For the FA 20 I brought the > tripod closer by a few cm. > All apertures tested from wide open through F16. > All photos processed the same in PS. > All comparisons done at Actual Pixels. > > My tests are for sharpness across the field. Obviously this test > doesn't > allow for evaluation of bokeh. Both lenses seem well corrected for > distortion. > > My usual caveat: I conduct these tests for myself. I post them as a > public service in case anyone else finds them useful. If you don't > find > the test useful, you are free to ignore it. > > Wide open (DA 21 @ F3.2, FA 20 @ F2.8): > The FA 20 is very slightly sharper across the field. Emphasis on > "slightly." > > F4: > The FA 20 seems a bit sharper in the center. The lenses are about > equal > at the edges and in the corners. > > F5.6: > The FA 20 seems a bit sharper in the center and in the corners. The > lenses are about equal at the edges. > > F8: > The DA 21 is just slightly better in the center and in the corners. > The > FA 20 seemed a bit better at the edges. > > F11: > The DA 21 is a bit better in the center and at the edges. The FA 20 > seems slightly sharper in the corners. > > F16: > The DA 21 was slightly better across the field. > > The bottom line is that these two lenses are essentially equal in > sharpness. The FA 20 has a slight edge from wide open through F5.6. > From > F8 through F16 the DA 21 has a slight edge. But you have to go to > extreme enlargement to see these differences. At more moderate > enlargement one would have a hard time telling these lenses apart. > > Joe > > > -- > PDML Pentax-Discuss Mail List > [email protected] > http://pdml.net/mailman/listinfo/pdml_pdml.net -- PDML Pentax-Discuss Mail List [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net
