Performance
The lens performed very well. Autofocussing was accurate and the lens simply glided to the correct focus point, though not very rapidly. The focussing was sure-footed with no hunting whatsoever. The VC function performed very well too. I was able to get a four stop advantage in shutter speed just as claimed by Tamron. This is truly good performance since many lenses fall short of claims on this feature. The resolving power was very good and should be capable of 20x30 inch prints comfortably. Even when fully open the lens remains sharp, but stopping down improves things a lot. Its optimal aperture is around f/4.5. The edge sharpness was very good too. However, at 70mm the sharpness decreases marginally. There was no distortion with the D7000 body. On the D700 the lens exhibited visible barrel distortion at 24mm and at 70mm it had some pin cushion distortion. Focal lengths from 35mm to 50mm were excellent with practically no distortion. This is the range to be used for critical work. There was no corner light fall off (vignetting) on a D7000 body. On the D700, at 24mm focal length, there was light fall off to the extent of 2 stops when fully open and about one stop at f/5.6. Vignetting reduced progressively with narrower apertures and longer focal lengths. It was negligible at about f/5.6 at 70mm (less than 0.5 stop). Test shots taken even with bright light sources in the frame exhibited minimal flare and practically no chromatic aberration. Contrast was very good. All in all, an excellent performer.
Value for Money
The MRP of this lens is Rs.77,800. This is a reasonable price since its peers from other camera manufacturers run well into six figures! Also, this is the only lens in this focal length range and speed that has a stabilisation function. The performance is on par with the best. The lens represents excellent value for money.
SPECIFICATIONS
Lens Model : SP24-70mm F2.8 Di VC USD Lens construction : 17 elements in 12 groups Closest focussing distance : 0.38m or 14.9” Max. reproduction ratio : 1:5 Diaphragm blades : 9 ( rounded) Filter/ attachment size : 82mm Diameter x length : 88.2 X 108.5mm
approximately Weight : 822gms (approximately)