70-200 vs 150-600
Nikon 70-200 F4 vr lens at 200 mm; Sigma 150-600 C at 600 mm, both on tripod.
Different photo distance, so the photo's have the same size.
the upper is the 70-200 pic at 200%, below the Sigma pic, 600mm, at 200%.
I think, fine tuning has done his job...