Originally posted by Belnan According to DxO sharpness is measured over all apatures.
DxO scores are bad and confusing. But not as bad as some comments here suggest.
The DA15 scores last for a reason and I'll explain why. I personally love that lens, it is a unique offering in the Pentax line up noone else has.
DxO has 3 easily accessible scores:
- A: The DxO score which is a score of how much human visible information a camera/lens can capture in very low light. Here, a fast lens always wins if it is reasonably fast wide open. Here, the DA15 is rated low already because it is a slow lens.
- B: The P-MP score, which "only" averages some sharpness at the best aperture, weighting over the entire image field.
- C: Often overlooked but my preferred score: Mid light use case score, same as DxO score but for very good light.
While the DA15 scores only "14" at A, it scores a solid "30" at C, both scores taken at F/5.6 btw ...
The DA15 would score somewhat better if it wouldn't have extremely soft corners (I'd call them unusable) fully open. Clearly visible at the DxO field map. I am surprised actually that the mid light score didn't peak at F/8, an fstop I always try to use with that lens. The DA15 is great, but for it to be this small, it is only really useful at daylight. The DxO score reflects that.
So, in summary, the DxO scores do make sense but are incomprehensible to normal photographers.
My #1 complaint: the DxO scores violate the principle of divide and conquer: First, divide a problem into manageable subproblems, then solve each of it individually. We already know what a slow aperture means. We do not need no stinking DxO physicist to factor this well known fact into the question how sharp a lens it, making the resulting answer a mess.