Friday, January 12, 2007
Wide-Angle Lenses For Digital
Yes, you can do wide-angle photography with a D-SLR!
For really wide-angle fans, the D-SLR manufacturers and independent lens makers offer a number of very short focal-length zoom lenses optimized for use with APS-C-sensor D-SLRs. The accompanying chart lists these and other wide-angle lenses for D-SLRs, but essentially they start with a 10mm, 11mm or 12mm focal length, which on these D-SLRs is equivalent to 16-18mm on a 35mm SLR-extremely wide-angle. These are terrific choices for wide-angle fans because they provide everything from superwide-angle to moderate wide-angle in a single package, allowing you to adjust framing in tight spaces and minimizing the number of lens changes, which helps keep dust off the image sensor.
Each D-SLR manufacturer and independent lens maker gives its APS-C D-SLR lenses an identifying code. The Canon designation is EF-S, Nikon and Tokina are DX, Pentax is DA, Sigma is DC and Tamron is Di II. Because APS-C image sensors are smaller than a full 35mm image frame, lenses designed for cameras with these sensors don't have to produce as large an image circle. This allows for smaller lenses that send light rays more directly into the image sensor's pixels for better image quality, but means the lenses can't be used on 35mm SLRs or full-frame D-SLRs, because they'll vignette (in some cases, they can't even be mounted on full-frame camera bodies).
The Olympus Zuiko Digital lenses are designed specifically for Four Thirds System D-SLRs (currently, the Olympus E-1, Evolt E-330 and Evolt E-500, and the new Panasonic Lumix DMC-L1), which have even smaller image sensors-17.3x13mm, with a 2x focal-length factor.
You can use compatible film-camera wide-angle lenses on your D-SLR, of course; they just won't provide as wide an angle of view. With an APS-C format D-SLR, any lens of 24mm or shorter will provide noticeable wide-angle capability.
What To Look For
When choosing a wide-angle lens for your D-SLR, your first concerns are that the lens in question will provide the desired angle of view and work on your camera. If you're used to 35mm SLRs, you can determine the focal length required to provide the equivalent angle of view by dividing the 35mm camera lens' focal length by 1.5 for an APS-C-format D-SLR or by 2 for a Four Thirds System D-SLR: If you want an angle of view equivalent to a 24mm lens on a 35mm camera, you'll need a 16mm lens on an APS-C D-SLR or a 12mm lens on a Four Thirds D-SLR.
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