Introduction Being lighter, smaller and more accessibly priced than Canon’s high-speed models the firm’s f4 L-series are popular with professionals and amateurs alike. The current 17-40mm f4L USM version was introduced in 2003, weighs 1.1 lb (500g), and has 12 elements in 9 groups (including Super UD glass element), and features an ultrasonic type AF motor. At $839 it’s a rightly popular model, particularly with landscape photographers who have little need of the faster and more expensive f2.8 model. This new lens sits between the two and features a four stop optical stabilizer and a revised