Since my lens collection got quite big (bigger than I thought I'll ever want it to be), I've decided to start a little testing - maybe it will help somebody... :-)

Tested lenses:

• Canon 50/f1.8
• Tamron 17-50/f2.8
• Tamron 70-300/f4-f5.6
• Tokina 50-135/f2.8

All the images are 100% crops from center and some corner...

test @17mm

Tamron 17-50/f2.8

aperture	Center	Corner
2.8
4
9

test @50mm

Canon 50/f1.8

aperture	Center	Corner
1.8
2.8
4
5.6
9

Tamron 17-50/f2.8

aperture	Center	Corner
2.8
4
5.6
9

Tokina 50-135/f2.8

aperture	Center	Corner
2.8
4
9

test @70mm

Tamron 70-300/f4-f5.6

aperture	Center	Corner
4
5.6
9

Tokina 50-135/f2.8

aperture	Center	Corner
2.8
4
9