Sunday, February 21, 2010
Many owners of point-and-shoot cameras, and even many DSLR owners, favor automatic settings for exposure control, and for good reason. Automatic settings are available on most cameras, easy to use and deliver consistent results. They can control shutter speed, aperture, ISO or a combination of all three. Here’s how the typical exposure modes work:
• “P” for Program, a mode that automatically sets both the aperture and the shutter speed.
• “S” or “Tv,” for shutter priority. You choose the shutter speed, and the camera will select the aperture. In case you’re wondering, “Tv” stands for time value.
• “A” for aperture priority. You choose the aperture, and the camera selects the shutter speed.
• “M” for manual. You do it all.
In my mind, the “S” is the most useful auto mode. A common complaint by photographers is that their photographs are too blurry. This usually means that the shutter speed is either too slow to stop the movement of the subject or the photographer cannot hold the camera steady enough during the exposure. By choosing the “S” mode, and selecting a fast shutter speed, you can avoid these errors.
If you’re photographing sporting events, you’d better set your shutter speed at a minimum of 1/250th, preferably higher.
1/250th is probably a pretty good bet for most outdoor situations.
Once you move indoors you need to adjust down to between 1/125 and 1/60.
Below 1/60th it becomes tricky to hold a camera steady or capture movement without blurring unless you resort to flash. Here are some common problems with automatic settings.
• If you are in “S” mode and go indoors to take photographs with a higher shutter speed, the camera will seek out the larger apertures to compensate. Once the camera has reached its maximum aperture, though, it has nowhere else to go. You will have to pick a slower shutter speed or your photos will be underexposed.
• If you are in “A” or “P” mode, and are photographing indoors, you should set your camera to the largest aperture available. This will ensure that your camera continues to selecting the fastest shutter speed possible given the light conditions. Monitor your photos and note if your subjects are blurring or if you are not holding the camera steady. If that is the case, it’s time for flash. A note of caution. Many of today’s cameras can automatically adjust your ISO if you run out of elbow room with your aperture and shutter speeds. I’ll tackle ISO controls and information next week.