Light Exposure in Digital Cameras
A guide to Aperture and Shutter Speed
The task of choosing the correct digital camera can be both a time consuming and daunting experience without the right tools at your disposal. One of the things you can do to make your shopping experience more successful is spend some time learning about common terms used to describe the abilities of digital cameras. This article will focus on two terms related to light exposure in digital cameras: aperture and shutter speed.
Aperture refers to the size of the diameter (distance from one side of the opening to the other) of the iris when it is open at its largest point. Aperture is measured in the units F-stop. Try to remember that the smaller the F-stop, the larger the maximum lens opening on the camera. The sensitivity of the camera to light is controlled in part by the aperture.
If you are purchasing a new camera, you should look for product with an aperture range from F2.8 to F8, while advanced photographers may need a range closer to F1.8 to F16. A large aperture means that you have more leeway with lighting conditions when you are shooting. If you have a larger possible aperture, you will be more prepared for low-light conditions. To give you some perspective, the mid-range Z650 digital camera by Kodak offers both wide and telephoto options for aperture, which range from F2.8 to F8 and F3.7 to F8 respectively. If you see the term "Aperture Priority Auto Exposure", "A mode" or just "Aperture Priority" the product is referring to a mode where the user is only responsible for setting the aperture. When the shutter button is pressed, the camera determines the best shutter speed setting. This is sometimes referred to as semi-auto mode.
Aperture is related in part to shutter speed. Shutter speed on cameras can range from as short as one eight-thousandths of a second up to a full thirty seconds. This time refers to how long light is allowed in through the camera lens when you hit the shutter (picture capture) button. Today's digital cameras generally offer both an automatic and manual shutter speed mode. For example, the new Kodak EasyShare Z650 has an automatic shutter speed range between 1/8th and 1/1700th seconds. The manual mode of the Kodak Z650 goes from eight to 1/1000th seconds.
It doesn't hurt to pay attention to shutter speed when you're picking out a new digital camera for yourself because there are some interesting techniques you can practice with a variable shutter speed. One example is using your camera to capture an object in motion. If you follow the object and have adjusted your shutter speed correctly, you can succeed in showing the object in perfect focus and yet a blurry moving background.
An interesting aspect to keep in mind as you look around for a digital camera is that aperture and shutter speed are related terms. These two aspects of a camera work together to control the amount of light that reaches your CCD, CMOS or other digital sensor. By shopping for a camera that offers you maximum aperture size and range of shutter speed, you will be giving yourself more options to shoot different kinds of photos.
In closing, a higher maximum aperture is better, as it allows more light to hit the sensor in your camera. A smaller minimum aperture size is also good, because it gives you more flexibility when lighting is abundant. A fast shutter speed means that you'll have greater ability to shoot fast moving objects and make use of a number of popular motion-based shooting techniques.
Phillipe Testanni is a photography hobbiest and author of articles about taking digital photographs for Elite-Cameras.com. Phillipe gratefully acknowledges the help and mentoring he received from Tom Samus.