NWA-PCUG Newsletter Article, September 2004
Digital Photography--Translating Photospeak
by Bill Moeller, Vice President
wmoeller@arkansasusa.com
(click to email author)


Although digital cameras tend to use similar terms, and to offer similar features at any given price level, they are not all identical. Some of the names of the controls used here (italicized terms) might be called by different names on your camera, and some of the features discussed here might not be available on your camera. But all of the concepts apply.

Tried reading your new digital camera's instruction manual lately? Mine is pretty clear, but it is 124 pages cover-to-cover and seems to assume that I already know what things like exposure compensation, white balance, aperture, and exposure index are. Do you? If not, you are probably not getting the most out of your manual, or your camera.

Overall, the camera is really a pretty simple device in spite of the incredible technology built into it. It has a lens designed to gather the light and focus the image from the scene to be photographed, a photo sensor to capture the image, an adjustable diaphragm to control the brightness of the image, a shutter to control the length of time the sensor is exposed to the image, and a microprocessor to "develop" the picture right then and there.

Everything follows from these basics. Every bell and whistle on your camera is there to give you control over composition, focus, exposure, and image quality. Not interested in all that control? Use the full automatic mode and forget all the rest. All you have to do is look in the viewfinder, compose the scene, and push the button. If alarms go off, the camera is most likely telling you it can't handle this one on full automatic. Otherwise, you got a good one.

Want more control? Read on.
The simplest way to get just a little more control is to use Scene Selection to select the type of picture you are about to take. Choices typically include Portrait, Landscape, and one or two others. In this mode the camera selects preprogrammed settings for each control that will probably do a pretty good job for that type of picture in most cases.

Experienced photographers ignore these settings, preferring to select the various control setting for themselves. But doing this requires a deeper understanding of how a camera works. With focus, for example, the camera focuses most sharply on a specific object or area in the scene. At wide lens apertures, everything closer or farther away will be noticeably less sharp. At smaller apertures, this effect will be far less noticeable. If available, Aperture Priority mode can be used to control this "depth of field," while allowing the camera to automatically select the shutter speed necessary for correct exposure.

At slow shutter speeds moving objects will appear blurred, at high speeds they will appear frozen. Shutter Speed Priority mode, if available, can be used to control the amount of blurring, depending on the photographer's wishes, while allowing the camera to automatically select the aperture necessary for correct exposure.

Manual mode, if available, can be used to control both aperture and shutter speed at the same time. The trick is to select a combination that gives the desired effect while still giving proper exposure. If this is not possible, changing the ISO setting (discussed below) might do the job.

Proper exposure is critical in producing a good photograph. Regardless of the exposure mode used, proper exposure might not be possible, or you might want to deviate from "proper" for creative reasons. You might even not be sure what proper is and want to hedge your bets. Several controls are available to meet these needs. ISO controls the amount of light necessary for proper exposure. The higher the setting, the less light required. But the higher the setting, the "noisier" the picture. ("Noise" is sort of like grain in a high speed film.) A good rule of thumb is to keep the camera set on the lowest available ISO setting, changing it only when there is compelling reason to do so.

EV (exposure value, or Exposure Compensation) allows you to force the camera to overexpose or underexpose the scene by a fixed amount relative to what it would otherwise do. For example, the camera will typically underexpose a snow scene because it is trying to make a middle gray out of all that white snow. EV can be used to compensate for this by telling it to add some more exposure to the scene.

If you suspect that a little overexposure or underexposure might produce a photo more to your liking, and you're not sure which, use Exposure Bracketing. This time honored procedure, widely used by professional photographers, produces three photos in rapid succession--one "properly" exposed, one underexposed by a set amount, and a third overexposed by the same amount.

Closely related to exposure is White Balance. We humans have an incredible ability to perceive what we see in "normal color" even when there is a strong color cast in the scene before us. Your digital camera attempts to do this same thing automatically. When you believe it will not do the job properly you can override the automatic setting by using the White Balance control. A good rule of thumb here is to leave this control on automatic unless there is a compelling reason to do otherwise.

Image Size, sometimes called Resolution, is used to specify the number of pixels in the recorded image. The more pixels, the finer the image will be. It will appear sharper and more detailed. But, the more pixels, the faster you will fill up your memory card. A good rule of thumb here is always use the maximum number of pixels available. If you fill up your memory card too fast, buy more memory cards.

Image Quality typically allows you to choose between storing the image in a tif or a jpg file. There is usually only one tif choice, but several jpg choices. The difference is that tif stores the image with zero loss, while jpg compresses the image for storage and loses information in the process A good rule of thumb here is to use the finest (least lossy) jpg setting available. As with Image Size, if you fill up your memory card too fast, buy more memory cards.

If you have an Auto Focus control, your viewfinder or viewing screen will very likely show what area of the scene the camera is focusing on. Explore the options and see which you like. If you choose an option which focuses on the center of the scene, you will have to fight the tendency to always locate the principal subject dead center in the picture. You can get around this by pointing the camera directly at the subject, depressing the shutter release half way until you achieve AF Lock and AE Lock, recomposing the scene without releasing pressure, and then depressing all the way to take the picture. (Some cameras have additional locking controls so you can lock focus on one part of the scene, and exposure on another.)

Digital Zoom is worthless. Ignore it. All it does is digitally enlarge the image and crop it, You can do this much better on the computer, with a higher quality result.

Photo Effect includes options such as Sepia (a brown tone effect) and Solarize (which produces an exotic mixed positive/negative effect). These are also much better done on the computer.

Sharpness is another control best left to the computer after the picture is taken. The need for this adjustment (if any), and the proper degree of adjustment, can best be seen with a large image on the computer monitor.

Red Eye Reduction partially or completely eliminates the "red eye" effect when using the flash to photograph people or animals in dim light. Very useful when it works, but you might need to compensate for the startled or stiff reaction to the preflash and the resulting delay in taking the picture.

Burst mode, like exposure bracketing, allows you to hedge your bets. It fires off several shots in rapid succession to increase your chances of taking the picture at just exactly the right time in a fast-moving situation. Very useful for sports action, and for catching that elusive fleeting expression when shooting your favorite subject.

Hologram AF (AF Assist Beam) allows you to use autofocus in very dim light. It does this by projecting a beam of light on your subject for your camera to focus on. It is extremely useful, but limited by how far the camera can throw the light.

If your cameral has a Histogram display, learn to use it. It shows graphically the complete distribution of light values in a scene, and how they will appear on the picture you are about to take. There is no more powerful tool available on your camera for getting the exposure right, but it is very difficult to learn to use to full advantage. If you are serious about your photography, and want complete control, it is worth the effort.

NightShot and NightFraming are uncommon, but useful features. NightShot uses infrared light projected by the camera to take pictures in total darkness. The colors in the picture are strange because of the light source, and it is probably best to desaturate the image on the computer and view it in black and white. NightFraming uses infrared light to focus and compose the image in total darkness, then uses the flash to take the picture. Colors in this case are normal.

Finally, Macro mode is used to take extreme closeup shots. It enables you to get closer, and to get higher quality shots while you're there. But do remember to reset this control when you go back to normal shooting distances.

In photography, as in computing, the jargon is endless. I have tried here to shed some light on some of the more common and useful terms. If I have omitted one that is giving you trouble, send me an email or raise the question at one of our meetings.

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