"stopped down a bit the lens sharpens right up"

Jon wrote in post #17824759
"Need to", no, not in the sense that you'll get unusable pictures when you shoot wide open. However I don't know of any lens, prime or zoom, from any manufacturer, that won't gain a little in resolution by being stopped down 1-2 stops below its' fastest aperture.

Thank you for that affirmation. I hear so much lens trashing because it's not as precisely sharp wide open as when stopped down just a bit.
In a perfect world in which the laws of optics and manufacturer tolerances don't apply, their cries might have some logic.

I'm hearing the same trash against the powershot G5X, ( my newest addition), even though on mine I must look closely to see the difference.

chuckmiller wrote in post #17825997
All Canon L lenses are pricey. Some are STUPID pricey.

*shrugs* you get what you pay for I guess

Also, I almost never stop down any of lenses unless I need the DOF

I usedy 400 5.6L a lot. Many thousands of shots. I could not detect any increase in sharpness stopping down. There was more light fall off, vignetting if you prefer, when wide open. Even when I tested with a 1.4 TC I could not detect any benefit in sharpness when stopping down. I found 300 F4 IS to be similar.
I had a 200 2.8L which showed improvement qhen stopping down to F4 and again F5.6.
70-200 2.8L II, while showing increased sharpness when stopping down, F2.8 was still very sharp and only reason I would stop down was DOF. When used with 1.4 TC increased sharpness when stopped down was more noticeable.
My Sigma EX 50 1.4 is the most impressive wide open lens regarding sharpness I have ever owned.
Tests done on 16-35 F4 IS show it tends to be sharpest (at some focal lengths) at 5.6 and F4 as good as F8.

So while stopping down increases sharpness and most lenses being sharpest at F8-F11 are often stated, theu are just broad rules with plenty of variation regarding specific lenses.

Further, sharpness is often overated IMHO. If thin DOF is desired, achieving that DOF is more important than ultimate sharpness. Quality of the blur os also important to me.

I've slowly upgraded my lenses to the point where I am happy to shoot every one of my lenses wide open, every time. It took time and money, of course, but was worth it. Choosing an aperture for a shot is about optimising DOF and shutter speed, not worrying about the lens sharpness.

JeffreyG wrote in post #17826003
Does this mean you are not a Leica shooter?

Touche