Tamron 18-270mm f/3.5-6.3 Di II VC PZD - £480/ $500
This lens is far from a simple revision of its predecessor. With added PZD (Piezo Drive) autofocus, it's much smaller and lighter than the first 18-270mm, has 16 elements rather than 18, a smaller and lighter VC (Vibration Compensation) system and a filter thread of 62mm not 72mm.
It's about the same size and weight as most 18-200mm lenses, and 115g lighter than Nikon's. Handling is assured, but the sluggish f/6.3 maximum aperture at the telephoto end makes handheld a challenge despite the four- stop stabiliser.
Performance
Autofocus is much quieter than with the original 18-270mm's basic motor, but it's no quicker. Sigma's ultrasonic motors are faster. Sharpness is disappointing at both ends of the zoom range, and adequate in the middle region. Barrel distortion is also pronounced at 18mm, switching to pin- cushion distortion at mid-range zoom settings. Colour fringing is also an issue at either end of the zoom range.
Sharpness
At f/8, sharpness is pretty good at focal lengths around 135mm, but less inspiring towards either end of the zoom range.
Lab test at f/8
Sharpness at wide angle: 1172
Sharpness at mid range: 1344
Sharpness at telephoto: 885
Fringing
Apart from in the central region of the zoom range, fringing is a major issue, with some of the worst results on test.
Lab test at f/8
Fringing at wide angle: 2.33
Fringing at mid range: 0.6
Fringing at telephoto: 3.37
Distortion
Pronounced barrel distortion switches to high pin-cushion distortion as you zoom from wide-angle to mid-range settings.
Lab test at f/8
Distortion at wide angle: -4.02
Distortion at mid range: 1.25
Distortion at telephoto: 1.09
Image quality verdict
The extreme 15x zoom range is an undoubtedly good feature to have, but brings with it a fairly major compromise in terms of image quality.
Taken at 18mm (min)
Taken at 270mm (max)
