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Understanding Camera Lenses
How different camera lenses affect your photos
 There are several types of lenses available for Digital SLR cameras, and
choosing the right lens for the type of photo you want to take is critical to
capturing a quality image. in other words, you need to match the lens to the
job.
Here is a run-down of the different types of camera lenses available:
- Fixed Focal Length Lens - These lenses have no "zoom" capability so the only way
to zoom in or out is to physically move closer to the subject or farther away
from it. Fixed
Focal Length lenses are "faster" than zoom lenses (they have a wider aperture).
Fast Fixed Focal Length lenses offer two advantages over zooms:
- A faster lens allows a shallower
depth-of-field which can "isolate" the
subject by blurring a "busy" background. A prime example is placing a bird in
sharp focus while the forest in the background is blurry.
- A faster lens allows faster action-freezing shutter speeds to be used - even
under low-light conditions. With a fast lens you can take clear, stop-action
photographs at basketball games, indoor track meets, etc. You can even get a
great picture of a child swinging a bat a piñata!
- Zoom Lenses - Zoom lenses allow you to easily and quickly adjust the focal
length of the lens to "zoom" in or out, bringing more or less of the subject into
view.
Zoom lenses have a couple of advantages of their own:
- A zoom lens gives you more flexibility in taking different kinds of
photographs without having to move to change the amount of the subject that
shows up in the picture.
- A zoom lens necessitates fewer lens changes which can allow dust to
settle on the sensor.
Most point & shoot digital cameras offer a zoom feature as well. Some offer a
digital zoom where a percentage of the pixels are actually removed from the
image with the resulting pixels brought closer together - simulating a
zoom effect. The actual focal length of the lens doesn't change. The problem
with using a digital zoom is the resulting image is typically of very poor
quality.
The better point & shoot digital cameras have an optical zoom lens that
works much like a zoom lens attached to a Digital SLR camera. You press a button
and the front glass of the lens actually moves in or out changing the focal
length. If you're considering a point & shoot camera, do yourself a favor and
purchase one with an optical zoom lens.
- Macro Lenses - A macro lens will allow you to take close-up photos of very
small subjects - such as a bee or the stamen of a flower. Quality macro lenses
tend to be pricey compared to the cheaper "close-up" lenses sold by some
companies, but if you're serious about doing macro photography you'll need to
cough up the bucks for a true macro lens.
- Fisheye Lenses - If you need a really wide field of view - say 180 degrees -
you'll need a fisheye lens. Circular fisheye lenses produce a circular,
distorted image but the effects can be quite pleasing to the eye with the right
subject under the right conditions.
- Lens Doubler - A lens doubler isn't really a camera lens in itself - you
can't just stick one on a camera and start taking pictures. Lens doublers work
in conjunction with a regular lens by mounting between the lens and the camera
body. By using a 50mm lens along with a lens doubler you effectively end up with
a 100mm lens.
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"Digital Photography Primer"
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