| 18-125 Dc vs 28-70 f2.8 EX vs Pentax 35mm f2.0 |
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I took 4 shots with each lens at f11, f4.5 and f2.8 (28070 and Pentax 35 only). Each image was centered on the same spot. I used a tripod and MF for each shot. Most of the sets of four from a particular lens/f-stop did not vary much if at all in sharpness. I shot Aperture Priority for the Sigma lenses and Manual for the Pentax with matching the shutter speed. The best of each set of 4 was selected. I was about 60 feet from the near signs in the picture - infinity for all practical purposes.
The images are in the gallery: http://www.pbase.com/sigmadslr/lens_issues. Here is how I recommend viewing them. Load the gallery thumbnails first. Then open three other windows and load the thumbnails into each. Now you can load the original size of each lens into the open windows and then click back and forth to compare. Notice how close they are in field of view. Be sure to compare the corners.
At f2.8: The Sigma 28-70 at 2.8 looks very very good, a lot better than the "legendary" Pentax. Color is very similar. At f4.5: The Sigma 28-70 at 4.5 looks very very good. The Pentax is better than the 18-125 which is wide-open at this point. The foreground (gravel) of the Pentax and the 18-125 look sharper than the 28-70. At f11: All three look very close. Your choice may vary depending upon what area of the picture you are looking at. Further thoughts: The Sigma lenses look slightly "warmer" than the Pentax, something that others have noticed in doing comparisons. This test supports other tests I have done with the 28-70 from the standpoint of it being very very good at the shorter end. |