![]() Zoom lenses also come in two main varieties: constant-aperture and variable-aperture. And the Sigma 18-300mm F3.5-6.3 is a wide to telephoto zoom lens with a very high zoom ratio. For example, the 24-105mm F4 DG OS HSM is a 4.3x zoom, while the huge 300-800mm F5.6 EX DG HSM lens is a 2.6x zoom lens. So, you can have a wide to short telephoto zoom lens with a higher overall zoom ratio than a telephoto to supertelephoto zoom lens. Here, the camera is zoomed all the way to 150mm (and panned slightly right) and as you can see, that’s a 3x closer view. Look at the shortest and longest focal length to determine the zoom ratio of a lens. ![]() Here is a view of a rock quarry made with the vintage Sigma 50-150mm F2.8 at 50mm on a Canon EOS Rebel T3i. All three of of these lenses offer the same maximum telephoto focal length, but the 60-600mm offers a much longer zoom range. The zoom ratio only relates to the difference between the shortest and longest focal lengths, so the 150-600mm F5-6.3 Contemporary and Sports lenses are 4x zoom lenses, while the 60-600mm F4.5-6.3 is a 10x high ratio zoom lens. So the 120-300mm F2.8 DG OS HSM is a 2.5x zoom lens and the 70-200mm F2.8 DG OS HSM Sports is a 2.8 zoom lens. A quick twist of the zoom ring can easily change the feel of the scene, and this is a key advantage of zoom lenses. Notice how the background is more abstract, even with the same F4.5 aperture as the previous shot at a wider field of view. Same scene, seen through the same lens, this time fully zoomed to 35mm. 1/400 F4.5 ISO 100 on a Canon EOS Rebel T3i. (It is common practice to round to the nearest whole number or major fraction.) Fall leaves seen through the Sigma 18-35mm F1.8 DC HSM lens at 24mm. So, for example, the Sigma 18-35mm F1.8 DC HSM and the 8-16mm F3.5-4.5 are both examples of 2x zoom lenses: 35 divided by 16 equals 1.95, and 16 divided by 8 equals 2. To determine the overall zoom ratio of the lens, simply divide the longest focal length by the shortest. Zoom lenses always feature two focal lengths in the name which indicate the shortest and longest focal lengths in relation to the 35mm/full-frame sensor. Zoom Ratio, and Constant-Aperture or Variable-Aperture Zoom lenses We’re also going to showcase images made with a variety of Sigma zoom lenses to illustrate key concepts. In this article, we are going to explore many facets of zoom lenses for digital photography and explain the terminology, key features and benefits of the different types of zoom lens. Which Sigma zoom lenses are right for you depends on your photographic intentions, budgets, and overall size constraints. Sigma offers a line of over 20 zoom lenses for DSLR photographers, ranging from wide angle zoom lenses, supertelephoto zoom lenses, and high-zoom ratio all-in-one lenses for both full-frame (DG) and APS-C (DC) digital cameras. ![]() A zoom lens allows for quick and easy re-framing of a scene while staying in the same physical position. This is in comparison to a prime lens, which only offers a single focal length. A zoom lens is a type of camera lens that offers the photographer a useful range of different focal lengths in a single lens. ![]()
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