Sigma APO 150-500mm f/5-6.3 DG OS HSM review by Stockholmviews.com, page 3
Sigma 150-500mm OS vs Sigma 80-400mm OS
Focal length vs sharpness @ F8 for Sigma 150-500mm OS and 80-400mm OS
Camera on Tripod OS off.
As you can se sharpness decrease as the focal length goes up (Both lenses).
I have restricted my evaluation to the 200-500mm range since I prefer to use
other lenses (Lighter) for shorter focal length.
Crop taken from the center square of different font sizes.
Font=Verdana regular.