Tamron AF 18-270mm f/3.5-6.3 Di II VC PZD - £495
This isn't Tamron's old 18-270mm with a PZD (Piezo Drive) autofocus motor fitted – this is a whole new lens. Optically, it's based on 16 rather than 18 elements, although they're still arranged in 13 groups. The vibration correction system has been revised, and while it proved good for a four-stop advantage, it's much smaller and lighter than the older system.
This is one of the factors that makes the 18-270mm much more compact than its predecessor, and little more than two thirds of the weight. The filter thread has also been reduced, from 72mm to 62mm. The PZD autofocus is a lot quieter than the standard micro motor fitted to Tamron's older 18-270mm lens. But because it isn't a ring-type ultrasonic system, it's still not particularly fast and it lacks full-time manual focus override.
Build quality is a step up from the older Tamron, and the jerky zoom ring has been updated with a low-friction replacement. However, zoom creep is a real problem. It shouldn't be an issue for handheld shooting, but it's a nightmare on a tripod. At least there's a zoom lock for safe carriage.
Sharpness is good and consistent throughout the zoom range, although the maximum aperture of f/3.5 is best avoided at the wide-angle end. Colour fringing is negligible at the centre of the frame, but poor around the edges, especially at each end of the range. Pincushion distortion is above average at medium focal lengths.
Centre sharpness at all focal lengths is good. The quality drops at the edges, but not as dramatically as on the Sigma lenses.
Green fringing at 18mm and 270mm is apparent. There's little sign of any colour fringing at the mid-point of the focal range.
Distortion at all lengths is average. At 18mm, barrel distortion is apparent, and pinch distortion is quite high at the mid-point.
Image test verdict
The Tamron has good centre sharpness at all focal lengths, and although there's a drop towards the edges, it's lower than most of the other lenses.