Are you ready to become a more creative photographer by making the step up from simple snapshot cameras to serious photographic tools? If you are, then the answer to the question, What are Interchangeable Lenses, is an important start.
A whole lotta lenses: Above, all of the lenses Nikon makes for its DSLR cameras.
Interchangeable lenses are lenses that can be mounted on a camera and swapped out for other lenses. Unlike fixed lenses, which are built into (mostly compact) cameras, interchangeable lenses provide the user with a wider choice of image-capture capabilities. While there are general-purpose lenses that cover the same range as lenses on built-in cameras, the optical quality is generally better. But the true power of interchangeable lenses is in the specialized lenses that are available.
Mounts and Cameras
Before we talk about the kinds of interchangeable lenses available, we need to look at the cameras that accept interchangeable lenses. They fall into several categories:
Above: Canon's entire line of lenses for its Digital SLRs.
DSLR: Digital Single-Lens Reflex cameras (which were preceded in the film era by simple SLRs) are made by Canon, Nikon, Pentax, Olympus, Leica, and Sony. These cameras have a reflex mirror and optical viewfinmder that allows you to see the actual image projected by the lens. Each DSLR brand has its own mount. Lenses made for a Nikon, for instance, will not fit on a Canon, and vice versa.
Above: Leica makes dozens of lenses for its line of high-end rangefinder cameras like the Leica M9. Here are four of them.
Rangefinder: Rangefinder cameras are specialized tools that are favored by documentary photographers and photojournalists. They consist of an optical viewfinder and focusing mechanism that lets you view the scene, not through the lens, but parallel to it. Leica is the only company currently making a digital rangefinder, but there are a handful of other companies (Zeiss and Voigtlander) that make film rangefinder cameras, which are still in demand.
Above: Panasonic's Lumix first-genration EVIL cameras with four lenses. This is a new kind of interchangeable lens system.
EVIL: Electronic Viewfinder Interchangeable Lens cameras are a relatively new breed that showed up in 2008. EVILs look like small DSLRs but instead of a reflex mirror viewing mechanism, they use electronic viewfinders, which are basically very small screens that display images that you view through the built-in viewfinder. Olympus, Panasonic, Samsung, and Sony currently make EVILs and we can expect more companies to jump on the bandwagon. The mounts for EVILs are not compatible with DSLR lenses, although there are some adapters available that allow users to mount DSLR or rangefinder lenses on Olympus and Panasonic EVIL cameras.
Above: Even smaller than EVILs, MILCs such as the Olympus EP series is the smallest interchangeable-lens digital camera system currently on the market.
MILC: Mirrorless Interchangealbe Lens Compacts are the smallest interchangeable lens cameras on the market, having first been introduced in 2009. They're also the newest and fastest growing category of interchangeable-lens cameras. MILCs generally look like compact cameras, but you can change the lenses. They generally lack built-in optical or electronic viewfinders. To view the image, you need to look at the big LCD monitor of the back of the camera, just as you would do with a typical compact camera with a built-in lens. However, most models have either optical or electronic viewfinders available as optional accessories which can cost around $200 in addition to the price of the camera.
When choosing an interchangeable lens, you have the option of Prime lenses (which are a fixed focal length (35mm, 50mm, 200mm, etc.) or Zoom lenses (a typical wide-angle zoom might be an 18-35mm, a mid-range zoom, 28-70mm, and a tele zoom 70-200mm). Let's look at the advantages and disadvantages of primes vs. zooms.
Advantages: Generally, prime lenses are optically better than zooms, and are “faster”. A faster lens means it has a wider maximum aperture, such as f/1.4 or f/1.8, which lets in more light and lets you shoot in low-light situations without a flash or tripod. Prime lenses are smaller and lighter than zoom lenses, which makes them better for unobtrusive shooting. While zoom lenses might be jacks of all trades, primes do what they do very, very well. Different prime lenses are designed as “specialists” in macro, portrait, sports, wildlife or other forms of photography. Finally, prime lenses can be less expensive than zooms, although top-line pro primes with the best glass and construction available can cost thousands of dollars.
Disadvantages: Prime lenses don't zoom, which limits you when composing an image. Many photographers are willing to sacrifice speed and a little bit of optical quality for the flexibility of a zoom.
Advantages: Zoom lenses give you the flexibility to quickly compose or recompose an image without having to change where you are standing. Low-cost zoom lenses are surprisingly light and some offer a long zoom range; many zoom lenses have built-in shake reduction, which is effective in letting you shoot handheld in subdued light without flash. High-end zoom lenses can produce images with quality that rivals prime lenses, have wider apertures, and are made with higher-quality glass elements. Wedding photographers, photojournalists, sports photographers, and travel photographers may prefer zoom lenses because one lens can do many things well.
Disadvantages: Those low-end zooms are so light because compromises were made; apertures are smaller, and get smaller still as you zoom in. A typical kit lens's widest aperture is f/3.5 at the widest setting but may be as slow as f/5.6 by the time you reach its longest telephoto length. This is known as a variable-aperture lens. There are zoom lenses with wider apertures that remain constant throughout the zoom range, and while these are more desirable, they're also bigger, heavier, and more expensive.
Above: Lensbaby produces an unusual, distinctive lineup of specialty lenses for creative photographers.
There are lenses specifically designed for portrait and wedding photography, sports and wildlife, photojournalism, architecture, macro photography and more. Some lenses serve overlapping, specialized purposes, but would not be considered “general purpose” lenses.
Some lenses, such as Perspective Control (PC) lenses (right: Canon 24mm TS lens), let you tilt and shift the lens, roughly mimicking the kind of controls over linear distortion that you have with view cameras. These are used by architects who need to have lines of buildings they photograph to appear straight, and not “leaning”, a common problem.
Other lenses, such as the Lensbaby line of optics (above), allow you to more selectively blur areas of an image, creating dreamlike effects. These lenses have become very popular among pros who want to show a different, creative effect.
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