DIY Network

Zoom Photography: The Basics and Pitfalls of Using Zoom From "The Whole Picture" episode DTWP-108

	Zoom and telephoto photography is achieved through increased lens focal-length.
	A zoom lens on a typical digital instamatic camera.

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Are you disappointed with the performance of the zoom lens on your digital camera? The Whole Picture host Erin Manning understands the frustration many beginning photographers have when taking telephoto pictures and has some tricks up her sleeve that will really help you get better results.

Most digital cameras have a zoom-lens function, but that doesn't guarantee that you'll get good telephoto pictures. Knowing a few facts about digital cameras and types of zoom features they use can help ensure that you take the kind of photos you're looking for. In this episode, Erin talks about some of the pitfalls of using a zoom lens, offers pointers on how to get the most out of it and illustrates the difference between the optical and digital zoom functions on digital camera. Finally, she demonstrates tools for cropping and "zooming in" on an image using photo editing software.

Materials used in this episode:

Digital camera with zoom function
Camera owner's manual
Tripod
Computer with image-editing software installed

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	Figure A
	Figure B

Digital Cameras and Zoom-Photography Basics

Zoom lenses can be used to give the effect of "bringing you closer" to your subject, and also can impact the focus or depth of field in your photos. For example, you could use a powerful zoom lens to focus in very close on a particular subject such as a flower, while at the same time providing a narrow depth-of-field, resulting in the subject being in clear, sharp focus but the background and foreground fading into soft focus (figure A). The zoom function allows you to "get close" to elusive subjects--wildlife, for instance--but can also help you visually isolate your subject in the image.

In the traditional sense, a zoom lens works in a manner similar to binoculars. The further apart the two main lens elements are in a zoom lens, the greater the magnification. Digital cameras typically list number designations with respect to their zoom capabilities, usually accompanied by an "X." The "X" refers to the "times" or amount of magnification -- e.g., 2x or 4x. But on digital cameras, there are two types of magnification in use. One is optical, achieved in much the same way as traditional photography--through the optics of the lens being used. The other is digital zoom, which is essentially just a digital magnification trick that the camera does internally by "enlarging" and "cropping" the image--much the same way you might enlarge and crop an image using a computer and image-editing software. These two methods may be used singly or in combination, and promotional materials on most cameras will list them separately and as a "combined" total, ostensibly indicating they maximum amount of magnification you can achieve with that camera (figure B).

It's important to realized that optical zoom, which is achieved by the camera's lens, yields a higher quality magnified image than the effect achieved using the digital-zoom feature. Most professionals simply turn the digital zoom function on their camera OFF and rely only on the optical zoom to "zero in" on the subject. If you wish to digitally enlarge and crop a particular image, you can always do that later using a computer and image-editing software. And using your computer will offer you more options than most cameras, and you'll likely achieve better results.

Zoom Photography Pitfalls

Common mistakes made by novice digital photographers is to try to achieve "maximum zoom" by utilizing both the optical and digital zoom. This can result in pictures that are blurry, pixilated or both (figures C and D). Also, it's important to realize that, in addition to magnifying your subject, zooming in may magnify your photographic mistakes--such as blurring due to camera movement.

Figure C

Figure D

Figure E

To get professional looking telephoto pictures, it's important to understand the downside, as well as the upside, of a zoom lens. Zoom lenses can create a certain amount of distortion in your pictures. There are two main types of distortion to watch out for. The first occurs When you're up close to your subject and zoomed all the way out, watch for what's called barrel distortion. That's where things tend to be a little stretched around the edges or bulge in the middle (figure E). The second happens when you're zoomed all the way in on your subject, the lens will compact everything and make it look like things are closer to each other than they really are, and your picture will have no distinguishing subject. This latter situation is called compressed depth of field.

Another problem to look out for is camera shake. When you zoom in on a subject, because of the way the lens works, the amount of light that hits the digital camera's image-sensor is reduced, forcing your camera's shutter-speed to slow down. When your shutter speed gets below 1/250th of a second, there's the possibility that you will see any movement of the camera as blur in your pictures, making your pictures appear out of focus (figure F). When possible, use a tripod to help stabilize your camera so that you will minimize the potential for camera shake (figures G ).

Figure F

Figure G

	Figure H
	Zoom photography is ideally suited for photographing birds at your feeder on in your backyard. Avid birdwatchers often invest in serious telephoto and zoom equipment.

Another thing that most people don't realize is that, when you zoom in everything is magnified--including the dirt on your lens. This is why professionals always keep a lens-cleaning cloth with them and clean their lens often. Too often, beginning photographers ruin good shots by shooting with a dirty lens (figure H).

In the lesson that follows, Erin provides more tips on getting the most out of your zoom lens and additional insights into the functional differences between optical and digital zoom.

RESOURCES :

PC Photo magazine
Website: www.pcphotomag.com
Online version of the magazine devoted to digital photography and related technologies.

The Complete Idiot's Guide to Digital Photography
Model: 002864235X
Author: Steven Greenberg
Order this book from Amazon.com.
Prentice Hall
Paramus, NJ 07652

Digital Photography For Dummies
Model: 0764506463
Author: Julie Adair King
Order this book from Amazon.com.
Hungry Minds, Inc.

Complete Digital Photography
Model: 1584500077
Author: Ben Long
Order this book from Amazon.com.
Charles River Media
Website: www.charlesriver.com/