new 70-300L - am I nuts?

[Busted Knuckles]

I have to agree w/ CLS and perhaps expand slightly.

At f8 on a crop body in particular you will see the beginnings - significant - of the pin hole diffraction effect of the aperture. This actually degrades the image a surprising amount - you can see it in the ISO crops, (set up the same lens at 5.6 and f 11 and toggle between them) and I can see it my real world shots, if I do a side by side comparison.

I try to stay short of 6.3 if the DOF is appropriate.

[Scott Stephen]

I have to agree w/ CLS and perhaps expand slightly.

At f8 on a crop body in particular you will see the beginnings - significant - of the pin hole diffraction effect of the aperture. This actually degrades the image a surprising amount - you can see it in the ISO crops, (set up the same lens at 5.6 and f 11 and toggle between them) and I can see it my real world shots, if I do a side by side comparison.

I try to stay short of 6.3 if the DOF is appropriate.

Interesting point. I am adding that to my mental card file.