Chaliel wrote:
Most modern lenses have the optimum in the direction of wide open and bokeh (f2 - f4) but I am curious to know if there are lenses that have their optimum to small openings? (f10 or smaller)
DOF for landscape lenses.
One issue to keep in mind is that all lenses, from the best and most expensive to the cheapest and funkiest, are affected essentially equally by diffraction blur as you stop down the lens. No amount of lens design optimization can overcome that — it is simply an optical phenomenon that affects all lenses.
So the fact of the matter is that most good lenses perform pretty well at mid-range apertures of, say, about f/8 on full frame. One reason that a lot of landscape photographers are happy with zoom lenses, for example, is that their performance is in the same range as expensive prime lenses at the apertures typically used for landscape photography.
So, if the idea is that you are looking for some lens that is an extra-good performer at those smaller apertures, I’d make that a really low priority and instead simply look for a good lens that has other features that you need/want for your landscape photography. These may include focal length (or focal length range if you prefer zoom lenses), maximum aperture (whether that means a larger or smaller one is up to you), compatibility with your camera, size and weight (you might be carrying this on your back), and so forth.
Determining the “optimum aperture” on a lens is a tricky thing. For example, some lenses might have their best center sharpness at one aperture, but have their best average sharpness at a different aperture. If you use zooms, the optimum may very with focal length. Depending on your sensor’s resolution you may be concerned about best performance at a different aperture than another photographer.
My basic advice is to not worry about supposed optimized performance at small apertures, but instead to just focus on a good lens that aligns with your other needs.
Good luck!