imagemeister Loc: mid east Florida

I read it long ago and as I said a couple pages back that there is NO objective sharpness test in it !! Where have YOU been ??

wdross Loc: Castle Rock, Colorado

It can be very useful when deciding on which lens to buy. For example, the Olympus 7-14 f2.8 ( https://www.imaging-resource.com/lenses/olympus/7-14mm-f2.8-pro-m.zuiko-digital-ed/review/ ) and the Panasonic 7-14 f4 ( https://www.imaging-resource.com/lenses/panasonic/7-14mm-f4-asph-lumix-g-vario/review/ ). By using the sliders, one can see both lenses are really at their sharpest at f5.6. And the Panasonic loses less sharpest in the corners wide open. The Olympus is one step more open (f2.8 vs. f4) but loses some sharpest in the corners due to some chromatic aberration and slight distortion. Both lenses start falling apart in sharpness at f11 due to diffraction (the Panasonic slightly before the Olympus) and the Panasonic starts showing some slight corner chromatic aberration. The Panasonic goes one stop more to f22, but the sharpness is not good due to further diffraction and increased corner aberration. These charts basically show the lenses to be somewhat similar in sharpness, the Olympus having one more stop in aperture, and the Olympus is close to double the price for that one extra stop, and slightly sharper center at f4 and wide open. Now, does one "bite the bullet" for the Olympus extra stop, slightly sharper center wide open, and cost? Or does one go for the slightly smaller, lighter, not as fast, and less costly Panasonic? Only the buyer will know. But that is why the comparison charts for sharpness are important. If one was buying the Panasonic just because of the f22, it would be a poor reason to buy it. It pretty much comes down to the extra stop of light gathering versus the size, weight, and cost.