Wide-Angle Lenses For DigitalelptYes, you can do wide-angle photography with a D-SLR!
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By Mike Stensvold
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Page 2 of 5
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Fish-Eyes | The
widest-angle lenses are the fish-eyes. These provide a 180-degree angle
of view and come in two varieties: circular and full-frame. Circular
fish-eyes produce a round image in the camera’s standard rectangular
image frame; full-frame fish-eyes fill the frame, producing a
180-degree angle of view measured from corner to corner.
The only circular fish-eye on the market today is Sigma’s 8mm ƒ/4, and
it produces a circular image only with full-frame cameras (35mm SLRs
and full-frame D-SLRs). On APS-C D-SLRs, the image frame cuts into the
top and bottom of the circular image. (Sigma recently announced a new
optimized-for-digital version of this lens, but it produces the same
framing with APS-C D-SLRs.)
Three full-frame fish-eyes have been designed especially for APS-C
D-SLRs: the Nikon 10.5mm ƒ/2.8, the Olympus 8mm ƒ/3.5 and the Pentax
10-17mm ƒ/3.5-4.5 fish-eye zoom. You can use full-frame fish-eye lenses
designed for 35mm SLRs on D-SLRs, but that 1.5x magnification factor
greatly reduces their impact.
Focal lengths for full-frame fish-eyes overlap focal lengths for
rec-tiliear (“regular”) superwide-angle lenses. The difference is that
rectilinear lenses are corrected for barrel distortion and (in theory)
render straight lines as straight lines no matter where they pass
through the image. Full-frame fish-eyes exhibit barrel distortion and
curve all straight lines in an image except those that pass through the
center of the frame. And, of course, the fish-eyes have that 180-degree
(diagonal) angle of view, compared to around 115 degrees for an
equivalent-focal-length rectilinear lens.
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A considerably less costly alternative is to buy one of the
inexpensive 18-55mm zoom lenses usually offered as part of a kit with
entry-level D-SLRs. These are approximately equivalent to a 28-80mm
zoom on a 35mm SLR, giving you definite wide-angle capability; they
generally cost between $100 and $200. As a bonus, in most cases they
were designed specifically for use with APS-C-sensor D-SLRs, optimizing
image quality and keeping lens size down.
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