100% crop of a pepsi can taken at ISO 1600, under-exposed by about 1 stop, on a Canon 20D, with a 100-400 IS zoom at 400mm with 2 Kenko Pro 300 1.4x TCs plus a Tamron SP 2x TC stacked, for focal length of about 1600mm (probably really about 1400-1500mm, with all the exaggeration typical in TCs and lenses). Hand-held, 1/400s, f/32 (one stop down from the maximum f/22 with this combo).
Converted in ACR, sharpening default 25%, USM applied to top half of crop in PS - 250%, 0.8px, thrshld 7.