[frank]

Hi Wim and Serkan:



Thank you very much for your very detailed interpretation. I understand that for any f-value greater than 11 the diffration becomes serious, but I find that for landscape in many cases f8 (at around 20mm）does not give enough DoF, f11 maybe marginally, so I often stop down to f16 or f13 at least, in occasional cases I stop down to f22. I also read that many (or just some?) professional landscape photographers shoot landscape with f16, f18, f20, and sometimes even f22 (35mm camera). From an aricle I read that something like "beyond f11 the diffration will cause the sharpness of objects in the focus plane to decrease due to diffraction, but the overall sharpness of the image will increase due to the increase in the DoF， untill the diffraction limit of f22 is reached". Did I misunderstand something?



Perhaps I need more tests to see the effect of f11, 13, 16 and beyond. But for the following scenery my past experince tells me that f8 will not give enough DoF (I focused on the foreground stone then the background trees and mountains would be blurry), f11 or 13 maybe marginally OK, to ensure a large enough DoF I stoped down to f16 (Nikon 16-35mm f4 lens at 22mm):