Click for bigger image Click for bigger image Secondly, the flexibility of use. With a zoom lens, aphotographer can compose or cropped the image to his liking within the viewfinder without the need to constantly changing lenses or walking further forward or backward to get the desired framing. Third, only a zoom lens enables you to create a zooming effect during exposure using shutter speeds of 1/8 sec or slower. Try doing that with any single focal lenses. With the EF 70-200mm f/2.8L USM, not only does the photographer have all the above flexibilities but also a fast maximum aperture of f/2.8 for the entire zooming range. Unlike its predecessor, this lens has the added flexibility of a Mechanical Full-time Manual Focusing that permits manual focus override even when it is still set in the AF mode. << Back to Main . 1 . 2 . 3 . 4 . 5 . 6 . 7 . 8 .