Tuesday, May 5, 2009
Building The Ultimate Lens Kit
There are so many top-notch, high-tech, affordable lenses available for nature photography, it’s easy to assemble a collection that will give you the right tool for what you love to do
If you like to photograph flowers or bugs, you’ll want to add a macro lens to your kit. Macro lenses can focus close enough to produce a life-size image of the subject on a 35mm film frame and are optically optimized for close shooting distances.
Macro lenses come in several focal lengths. Shorter focal lengths let you move right in on a subject and still include some of the surrounding environment. Longer focal lengths produce a given magnification from farther away, handy when the subject is skittish. The longer working distance also provides more room for your lighting setup and reduces the chances that the lens will cast a shadow on the subject. (Serious macro shooters generally use electronic flash for three main reasons: It’s easily positioned anywhere you want it with today’s wireless off-camera flash feature; its brief duration at close range freezes subject and camera motion and negates the effects of wind; and it allows you to stop down for more depth of field—depth of field is very minimal at very close range.) Bear in mind that shooting from farther away also “flattens” perspective; if you want a feel of “depth” in a macro shot, it’s better to use a shorter macro lens and move closer to obtain the same subject magnification.
For even more magnification, you can attach an extension tube to your macro lens (or to any lens, for that matter). The advantages of extension tubes are that they allow you to focus even closer for more magnification, and they contain no optics to reduce image quality—they’re just spacers that increase the distance between the optical center of the lens and the focal plane. The disadvantages are a loss of light (you have to use longer exposure times or higher ISOs for ambient-light work), and the lens won’t focus out to infinity with an extension tube attached.
Many zoom lenses are touted as “macro,” but this usually just means they’ll focus closer than “non-macro” zooms of equivalent focal length. Most won’t produce better than a 1:3 (1/3-life-size) reproduction ratio. This is still good enough for a lot of semi-close-up work; just bear in mind that you won’t be doing 1:1 life-size macro work with these lenses.
A number of SLR landscape photographers are using tilt-shift lenses because they provide some of the versatility of the view camera. The shift feature allows you to get an entire tall object into the frame without tilting the camera up; this, in turn, keeps the film plane parallel to the subject plane and eliminates the “falling-over-backward” look so often seen in photographs of tall trees and cliff faces. The tilt feature allows you to tilt the plane of focus for tremendous control over depth of field at any aperture.
While the big challenge in designing a superwide-angle rectilinear lens is eliminating distortion, fisheye lenses revel in it. Fisheyes produce a 180-degree angle of view (diagonal with full-frame fisheyes; in any direction with circular fisheyes) and lots of barrel distortion. This relegates them to the special-effects realm, but fisheye effects can produce effective landscape images. One idea might be to point the camera straight up at dusk or dawn, when one horizon glows colorfully with the rising or setting sun while the other is dark.
Circular fisheye lenses produce round images rather than rectangular ones. Full-frame fisheyes, in effect, crop a rectangle out of the circular fisheye image to fill the image frame. This produces a somewhat unsettling effect—the image frame is normal, but all straight lines that don’t go right through the center of the image will be bowed outward.
Full-frame fisheyes are available for most popular 35mm and digital SLRs. Those designed for full-frame cameras provide a true 180-degree diagonal angle of view with those cameras and an angle of around 110 degrees when attached to an APS-C D-SLR. Canon, Nikon, Pentax, Samsung and Sony offer full-frame fisheyes for their small-sensor D-SLRs, while Sigma and Tokina offer them for several brands. Four Thirds System shooters can use the Olympus Zuiko Digital 8mm ƒ/3.5 fisheye.
Today, only Sigma makes circular fisheye lenses. Its 8mm ƒ/3.5 EX DG comes in mounts for Sigma, Canon and Nikon SLRs, providing a circular image with 35mm and full-frame models. The Sigma 4.5mm ƒ/2.8 EX DC provides a circular image with a true 180-degree angle of view with APS-C D-SLRs, and comes in mounts for Sigma, Canon, Nikon, Pentax and Sony D-SLRs.
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