Digital Photography's Finer Points (Part 2)

In part one of this series, we talked about the rule ofthan 1/250th of a second.
thirds. In this installment, we'll talk about depth of field.If a picture would be perfectly exposed at F/4 for 1
This technique will be used for every one of your250th of a second, you could change your combination
pictures and it's relatively easy.to F/16 and 1/60th of a second to get the same
Depth of field is the zone of focus in your picture.exposure. Even though the exposure would be the
Even with the simplest digital cameras, you'll have asame for both pictures, the amount of area in focus in
method to use to control what's in focus in yourthe photograph would be much more with the F/16
photograph. Most advanced 35mm film cameras havesetting. You probably won't be able to preview the
a depth of field preview button on them to let youdepth of field, but you'll see the results in seconds on
observe the zone of focus before you take thethe camera screen after you snap the picture.
picture. Only a very high end (read expensive!) digitalIf the reading on your camera screen says F/4 and
cameras have this feature.you want more depth of field, use the control to lower
You have two things at your control to make a goodthe shutter speed. Have the camera in the "shutter
exposure with your camera: shutter speed and F/stoppriority" mode. This is either "S" or "Tv" on the control
or aperture. To sum it up, these two features controldial. When you lower the shutter speed, the F/stop will
the intensity of light and the duration of light. The F/stopgo up and increase the area of focus for you. Most
is your main control for depth of field, but the shutterexperts agree that 1/60th of a second is the most
speed will come into play as you will see.amount of time to use for hand-held pictures. If it's on a
If you'd like more area to be in focus, you need a smalltripod, you can ignore this to some degree.
F/stop. To confuse matters, smaller F/stops haveIf you keep in mind that you're playing with light in
larger numbers. F/16 is a smaller opening than F/4.photography, you'll understand the concepts much
Much more will be in focus with the lens at F/16 thanbetter. How much light and for what duration is the
at F/4. If you use F/16, which is a small portal to let lightbasics of photography. Control this and you can control
into the camera, you have to let it in for longer duration.depth of field. It may sound difficult, but once you do it,
This is when shutter speed comes in. Keep in mindit'll be automatic.
that 1/60th of a second is a longer amount of time