koffiejunkie
Executive Member
- Joined
- Aug 23, 2004
- Messages
- 9,588
So max is not the sharpest - generally 2 or 3 stops more ... But then it declines?
Yes - diffraction takes over. Most lenses tend to be at their shapest at f/5.6 or lower (on crop bodies) but that's not a hard rule. That said, the differences you see on resolution charts are often not field relevant. For example, my 24-105L doesn't do too great in tests, but in real life it has a very even sharpness across the frame, and even at 18MP, it's difficult to tell it apart from my 50mm f/1.8, and compared to the 70-200mm f/2.8 L I rented, it holds its ground at comparable focal lengths.