Sigma's designation for lenses with a Helical Focusing system. These prevent the front element of a lens from rotating, making them ideal for filter use.
On sale: 4th Jul
If you're in the market for a lens, don't miss our complete guide to buying a lens, with 8 pages of tips and advice to help you make the best decision. Also in this issue we put three of Nikon's best DSLRs up against each other to find out what you get for spending more money. Plus much more!
Which of the new cameras announced so far this year are you most excited about?
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