WHICH IS THE SHARPEST APERTURE?

It is known that the best aperture, which will give us sharper images if we don’t have to play with depth of field for photos with great depth of field or very short, lies somewhere between the largest aperture-the smaller F number- and the smallest aperture-the largest F number. Normally the photographers were using the f/8 for the sharpest images.

But the other day surfing the Internet I found this interesting article by Ken Rockwell entitled Selecting the sharpest aperture showing this table:

For Nikon, Canon, Leica, Pentax and most 35mm cameras:

If the maximun aperture is.................The best aperture is

f/1.4.....................................................f/5.6

f/2.......................................................f/6.7

f/2.8...................................................................f/8

f/4..................................................................... f /9,5

f/5.6...................................................................f/11

f/8......................................................................f/16

So if I want maximum sharpness with my f1.4 Summilux I’ll shoot to f/5.6. With most of my f/2.8 fixed lenses to f / 8. With my 300 mm f / 4 tele lens at f/9.5, and with a zoom that opens at f/5.6 to f/11.

How Ken Rockwell did calculate this? I'm not going to argue but take pages and pages of numbers and mathematical formulas. For those crazy about math, not my case, this is the original page.