Field-test of the Canon EF 70-200mm f/4L USM zoom lens. Canon's EF 70-200mm f/2.8L USM zoom lens is a favorite among professional and advanced amateur EOS users. This lens, which is a successor to the EF 80-200mm f/2.8L AFD zoom lens, employs four UD (Ultra-low Dispersion) elements to effectively combat chromatic aberrations (also known as secondary spectrum), allowing pictures of high contrast and superior sharpness. However, excellent as this lens is, it also comes with a hefty price tag, nearly putting it out of most amateurs' reach. The alternative? They began to look at similar zoom lenses produced by the independent lens-makers. That was then. Now these EOS users really have a choice of owning an original Canon USM Lseries zoom lens. The lens in question is none other than the recently introduced EF 70-200mm f/4L USM. Reasonably-priced and weighing at a mere 705 grams, its overall diameter is about half the size of its f/2.8 'sibling'. Talk about the advances in lens technology, this USM zoom lens is more compact than the FD 70-21 Omm f/4 zoom lens that was made for Canon's manual focus 35mm SLR cameras. The EF 70-200mm f/4L USM lens has a filter size of 67mm diameter, as opposed to the 77mm used by the EF 70-200mm f/2.8L USM version. Like the f/2.8 lens, the f/4 version has no vignetting at the edges of the frame. The EF 70-200mm f/4L USM features the same optical performance as the f/2.8 version. Its compactness and light weight allow you to capture high quality images, whether be they travel, portraiture or nature. Canon EF 70-200mm f/4L USM Zoom Lense The f/4L Lense with the f2.8L version (Top) The lense attached to the EOS-1N Camera This lens has a high-grade finish and the external design is also based on the tasteful look of the EF 70-200mm f/2.8L USM. Zooming is done by moving the third and fourth of the five lens groups. However, the length of the lens remains unchanged throughout the entire zoom range. An internal focusing method utilizing the second lens group is employed, providing a minimum focusing distance of 1.2m/3.9 ft, which is the shortest in its class (the f/2.8 version's closest focusing distance is at 1.5m). Close focusing is one of the lense's features As opposed to the f/2.8L version, which utilizes four UD elements, the EF 70-200mm f/4L USM has one fluorite lens and two UD lenses to suppress secondary spectrum, which often causes decreased image quality in telephoto lenses, to an absolute minimum. For the record, one fluorite lens is equivalent to two elements of UD, which means the optical quality of the f/4 zoom, as mentioned earlier, is the same as the f/2.8 version. << Back to Main . 1 . 2 . 3 .