Taking Pictures with a
for showing on computer screens

Andre Sage of Nevada taking a picture, and this picture was taken by Daniel Adams of California

If you only want to see your pictures on computer screens you might want to shop for a digital camera differently than if you plan to print high-quality pictures on paper. That's because even fairly inexpensive digital cameras can take very good pictures if you just want to put your pictures on the Internet.

Nowadays digital cameras are so good that, for the purposes of producing pictures to appear on screens, you seldom need to worry about such things as how many megapixels you're dealing with, how much memory the camera has, etc. I'm using a Canon PowerShot SX160 IS costing $99 at Wal-Mart and that does all I want it to do. It even takes videos with sound, which can be uploaded to Websites such as YouTube.com.


Maybe 90% of my nature shots are taken close-up -- of butterfly wings, details of flowers, insects, mushrooms, etc. Many digital cameras may take wonderful pictures and be very expensive, but simply can't take close-ups unless you buy a special lens, which may be costly.

If you're at the camera store, how can figure out which cameras shoot close up? Numbers on the camera will let you know, but they can be confusing. Probably the best way to assure that you can take close-ups is to ask, or go onto the Internet and search on "macro cameras." You'll come up with lots of pages comparing various cameras with macro capability.

Cameras that can shoot macro shots of course also can take regular pictures. Different cameras have different ways of going from taking regular shots to taking macros. You just have to read in your manual to see how to "enter macro mode." It might be as easy as pushing the button with a flower on it.

When you're shooting very close up -- maybe at something half an inch or less from the camera lens -- you'll discover that you need to know about depth of field -- the depth of field being what's in focus. For example, if you're photographing an ant from the front, the face may be in focus, but the rest of the body will get fuzzier and fuzzier the farther it is from the face, and things behind the ant are just one big blur. In macro photography, we work with a very narrow depth of field.

There are tricks to getting "more depth of field," but you have to understand basic photography principles to take advantage of them.

For example, you get greater depth of field -- so maybe the whole ant is in focus -- by making the lens's aperture opening smaller. The aperture is the hole in your lens through which light passes when you click the shutter. A lens's aperture is measured in terms of f-stops. The larger the F-stop number, the smaller the aperture and the greater depth of field. My camera's f-stops range from f/3.5 to f/8. If I want to show the whole ant, I'll adjust the camera to f/8.

But, using an  f/8 means that your lens is using its smallest hole possible, and of course that lets in much less light than the biger hole of f/3.5, when means that your picture will turn dark.

You can overcome this problem by using a slower shutter speed, which is how long the shutter stays open when you click the camera. Slow shutter speeds let in more light, fast ones less. A fast shutter speed might be 1/2000th of a second, while a slow shutter speed might be 1/30th of a second, or even half a second, or several seconds, in which case you'd be making a "time exposure."


Most people have the urge to get everything they can into a picture, so they stand way back from their subject. The end result is a lot of look-alike, uninteresting pictures full of clutter. Therefore, when you take a picture, ask yourself what you want to show, and then go for that. The more specific your subject matter, the more interesting your image will be. And usually that means going in close

Here's another trick: Look at the subject being photographed with only one eye -- because that's the way your camera sees it. Very often something that looks good when seen with both eyes suddenly gets lost in background clutter when seen with just one eye!

But, the problem with slow shutter speeds is that if you're holding the camera your hands are always shaking the camera around and that will make fuzzy images. Also, at slow speeds your wildflower might move in the wind, also causing a blurry image. You can handle the problem with slow shutter speeds two ways: First, you can end the problem of shaking the camera as you hold it by using a tripod that keeps the camera steady. That won't help if wind is blowing your wildflower, though. The second trick is to increase your camera's sensitivity to light, by increasing its iso number.

So, to take good macro pictures you have to constantly be balancing in your mind your particular picture's needs in term of aperture, F-number, shutter speed, and ISO number. Change one of those, and it throws everything else off.

With good cameras with macro abilities, often just using "automatic" produces amazingly good pictures. However, the camera doesn't really know exactly what you're trying to show and it may focus on the wrong thing, or make wrong decisions in terms of how fast your subject is moving or how much depth of field you need. In the end, you just need to learn the basics discussed above, and read your manual so you can use the non-automatic manual setting.


When you take a digital picture your camera is creating an image file a computer can read. Moreover, usually the camera produces a file much too large if you only want to see your images on a computer screen.

For example,  when the picture at the top of this page was taken with average settings of a typical digital camera and the image was downloaded from the camera to the computer, it produced a file about 2.8 MB large. When I viewed that big file on my computer only a small part fit onto the screen.

One way to think about a digital picture's number of bytes is that bytes are nothing but bits of information. A piece of information might be something like "make this tiny point in the picture (the pixel) red. Another piece of information might be "make that red pixel a certain brightness."

Here's an important point about the picture at the top of this page. Though it started out in the camera as a file 2,800,000 bytes large, the picture you are seeing now is only 28,600 bytes large!

In other words, to make the picture usable for this page, I had to reduce it to a hundredth of its original size, from 2.8 MB to 0.028 MB, or 28 KB! For my purposes on this page, the camera gave me a hundred times more information that I needed, so that was wasted camera expense, wasted computer hard-disk space, and a waste of my time reducing the picture.


Lousy picture of ants on a windowThe nice thing about big digital-camera files, however, is that they produce images with a high resolution. That means that you can enlarge small parts of the picture and they'll still be sharp.

Ant on a window, picture by Daniel AdamsAs further explained on our page about using graphics programs, the rather crummy picture of ants on a window above and to the right began as a file 1.9 MB large (it's only 0.04 MB now). Before I reduced that picture to fit onto this page I enlarged the part of the picture with the ants in it and lightened it up with my graphics program so that now I have the picture of the bottom ant in the group shown at the left. If the camera hadn't produced a picture with such high resolution, it would have been impossible to get such a sharp ant-picture.