Fast telephoto zooms are often seen as key workhorse lenses for serious photographers. With premium optics, they offer top-notch image quality, along with plenty of scope for shooting in low light or using shallow depth of field. But typically weighing in at1.5kg, they require some commitment to carry around, and they're a major investment, too – Canon and Nikon's versions cost £2,000 and £2,650 respectively.
Naturally, third-party lens manufacturers have long sought to offer cheaper alternatives, but they've usually sacrificed features to achieve this goal. However, with its latest model, the SP 70-200mm f/2.8 Di VC USD G2, Tamron is pitching a product that on paper stands up very well against the big two. It includes an ultrasonic motor for fast and silent autofocus, optical image stabilisation, and weather-resistant construction;…