Originally posted by audiobomber The measurement may be taken at 5%, but the actual blur covers a lot more of the frame than 5%, as shown in the test photos I've posted several times.
Perhaps true of your copy; I haven't seen your test photos or read how you controlled for field curvature (did you specially construct a flexible test surface and then painstakingly experiment to reproduce the exact field curvature to match the DA15?)
Anyhow, on my copy, I can say that when the corners are in focus while shooting wide open - which is virtually never true in any real world shot - the noticeable softness is only around 5% of the frame, tops. And I'd guess those corners wouldn't even be present in the 16mm frame - that is, if you cropped the 15mm image to match the 16mm (especially after correctly for the distortion in the latter), what was left of the 15mm image would have practically no softness left in the corners.
Quote: You have claimed that the prime sharper in the center, but I can't see it.
Well, I don't have your copy of the 15, nor any copy of the 16-45 to compare with. All I can do is appeal to photozone numbers, which confirm the higher center resolution for the 15 at all apertures. Indeed, the *amount* of the difference may not be statistically significant. but I think that should be the bottom line: both lenses are plenty sharp. The decision between them should not be based on sharpness, but other facts. Much greater flexibility for the 16-45, small size and better IQ in ways other than sharpness for the DA15.
Quote: I'm not trying to say the 16-45 is the better lens, it is not. But the way people carry on about the 15mm is a little out there IMO, and the 16-45 deserves more respect than it gets.
Seems the 1645 gets plenty of respect, but maybe a few nay-sayers exist who exaggerate whatever deficiencies the lens might have, and you are trying to put those criticisms into perspective? Anyhow, I'd just observe the same is true for the 15 - lots of people praise it, a few naysayers, and I am trying to put those criticisms into perspective. Whatever small flaws these two lenses might have, their critics tend to blow them *way* out of proportion, and both are excellent lenses. Which is better for a given person depends on his/her needs.