Understanding the technology present in a lens is key to making informed decisions about which models you need in your kitbag. As with most photographic equipment, there are times when you will find that a feature does not offer a big enough benefit to justify the financial outlay, while in other circumstances it may be nearly impossible to create the images you need without a certain kit item.
With photographic lenses, the presence of such features may not be indicated as clearly as by having a physical switch, for example lens coatings or internal mechanisms. Often features will be referred to by prefixes or suffixes in lens nomenclature – those letters and numbers that make up often unwieldy and confusing lens names.
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This may make lenses seem like a dark and intimidating area of the market, but it really isn’t! Here, we’ll take an in-depth look at lens technology and the terms commonly used to indicate its inclusion. We don’t have all the lens manufacturers here, but we’ve tried to cover the most common ones.
Wide angle lenses
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Wide-angle lenses are generally accepted as optics with a focal length less than about 40mm, and today they cover everything down to 10mm for APS-C camera models and about 12mm for sensors full size. They are the optics of choice for professional landscape and travel photographers, but they find use in a wide range of shooting scenarios, from environmental portraiture to sports.
In some ways, it’s in this range of lenses that naming conventions have the most potential to confuse buyers. Indeed, as digital photography developed, there was a divide between the lenses needed for wide-angle photography on digital models and those that could be imported from film systems.
• The best wide-angle lenses (opens in a new tab)
Due to the smaller sensor area of early digital cameras and APS-C models available today, the multiplication factor applied to the focal length of mounted lenses means that wider than usual settings are required to produce truly wide-angle perspectives. However, the optical designs necessary to enable this mean that standard full-frame compatible lenses would be prohibitively large in size, weight and manufacturing cost. The solution was to produce digital-only lens lines, with smaller image circles to cover the smaller sensor formats. This allows short focal lengths without huge element diameters.
It is important to know which lenses are available for use on both crop-frame and 24x36mm sensors. Although there are now telephoto lenses with smaller image circles, this is generally for weight and portability advantages in mirrorless camera systems.
Other key features of wide-angle lenses are those that address the optical challenges of wide perspectives. These include chemical coatings and glass element designs to reduce edge fringing and geometric distortions, among others. Designations to look out for are ASPH, which denotes the use of aspherical elements for reduced distortion, and ED or ULD, which denotes a special low dispersion glass. These lenses are designed to more effectively focus light of different colors to the same point, thereby reducing chromatic aberration.
Just as ultra-wide lenses are necessary for stretched perspectives, shots of distant subjects cannot be achieved without the use of the telephoto lens. Whether you select a long telephoto lens, like a 500mm f/4, or a telephoto lens, like a 70-300mm f/4-5.6, these models allow the photographer to fine-tune their composition with precision, cropping details environmental undesirables.
These lenses are usually the choice of wildlife and sports photographers, especially models with focal lengths over 300mm. For this reason, the features built into telephoto lenses are usually designed to get the job done quickly – achieving focus quickly and allowing near-instantaneous recomposition.
• The best telephoto lenses (opens in a new tab)
Due to the higher magnification, camera shake is also a much greater likelihood when using a telephoto lens, so professional models almost always use image stabilization technology. This makes handheld shooting possible in lower ambient light, by varying the position of specialized lens elements to counteract camera lag. The effectiveness of this system varies from lens to lens, although most contemporary stabilizers allow a minimum of up to three stops of shake reduction.
On more advanced lenses, you’ll find additional speed-beneficial features such as supersonic wave autofocus motors, internal and rear focusing mechanisms, and the ability to apply focus adjustments. manual focus at all times, even when AF is active. While these might not be worth the extra investment if you rarely shoot in extremely fast-paced scenarios, for professionals and advanced enthusiasts they can be the difference between grabbing a shot and missing a winning opportunity.
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