Very sharp, outstanding quality lens, one of the best zoom lens what ever made by any one. Colour rendering is very nice, a well built lens both mechanically and optically. Little long and more heavy than prime lenses.
In my opinion, and for several reasons, this is the best 70-210 zoom lens ever designed and manufactured. Overall somewhat above average performance within its class, plus several notable design features. This later one-touch constant F3.5 aperture zoom features a unique "reverse" zooming cam in which the zoom collar moves forward to become a lens shade when zooming to the longer focal lengths. This, in conjunction with the bayonet lens hood, assures that the optics are always optimally shaded against stray light. The model 19AH has approximately 50% better overall resolution and contrast compared to the earlier two-touch model 52A. Macro optical performance is exceptional (for a zoom), reaching 1:2.66 life size at the 210mm position. Macro performance towards the corners of the field is superior to the earlier model. Achieving this high level of optical performance throughout the entire zooming and focusing ranges was no easy task.
(Source: Adaptall-2.com )