Tuesday, May 11, 2010
SLR vs. EVF
A new approach to interchangeable-lens camera systems gives photographers the option of smaller bodies. How do they stack up?
|How do SLRs and EVF cameras differ? The first thing you’ll notice is size and weight. Compare Nikon’s pro model D3S (6.2 inches tall and 2.7 pounds) and Canon’s enthusiast-minded EOS Rebel T2i (3.8 inches tall and 1.2 pounds) to the Olympus E-P2 at 2.8 inches tall and 0.6 pounds. Cameras shown here at actual size.|
Though the SLR remains the most popular type of interchangeable-lens camera, a new design is picking up steam. A hybrid of sorts—having a lot in common with fixed-lens compact digital cameras—these EVF cameras offer smaller, lighter bodies compared to SLRs. Will your next digital camera omit an optical viewfinder in favor of an electronic one?
THE VENERABLE SLR
For many years, the single-lens-reflex (SLR) camera has been the tool of choice for pro and serious amateur photographers, and for good reason. The SLR, be it digital or 35mm, is easily handholdable, offers a host of versatile built-in features, accepts a wide range of interchangeable lenses and provides eye-level, through-the-lens (TTL) viewing.
In an SLR, light coming through the lens strikes the SLR mirror, which directs it up to the focusing screen, where the reflected image appears laterally reversed (“mirror image”) due to the mirror. DSLRs have a pentaprism viewfinder, which re-reverses the image and sends it to the viewfinder eyepiece for easy eye-level viewing. Note that some lower-end DSLRs have pentamirror viewfinders rather than pentaprisms; the pentamirrors are more compact and less costly, though a bit dimmer.
|The Olympus E-P2 illustrates some key differences between EVF cameras and traditional SLRs like the Pentax K-x (below). Notice there’s no optical viewfinder on EVF cameras—you compose using the LCD or with an optional, shoe-mount finder, shown here.|
Advantages of this system include being able to see the image as it will be recorded regardless of lens focal length, no parallax (misframing with rangefinder cameras due to the viewfinder and lens “seeing” slightly different images) and relatively easy viewing in dim light.
When you press the shutter button to make an exposure, the SLR mirror flips up, out of the light path, so the light can reach the image sensor. The viewfinder image briefly blacks out while the mirror is in the up position, and the mirror’s movement causes vibrations that can reduce sharpness during long exposures at high magnifications. Many SLRs have mirror prelocks that allow you to lock the mirror in the up position after composing and focusing, then wait for vibrations to die down before making the exposure.
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