The JPEG format lets you decide what image size you want and how much to compress it. Compressed images make smaller file sizes but at the cost of good quality. The compromise in quality comes with the ability to store more images on a storage device.
RAW:
With the RAW format, images are not processed in the camera. Instead, they need to be processed on a computer. The RAW image contains all bits of the captured data, so the image size is very large. RAW images can be converted into other types of image formats.
Aperture refers to the diameter of a camera lens opening. Through this opening, light reaches the image sensor.
F-stop refers to the aperture value - F1.4, F14, etc. The smaller the number of the F-stop value the larger the lens opening, and vice-versa. F-stop values can range from openings as large as F2.0 to as small as F22. No one lens can have a full range of apertures. That is why there are different types of lenses such as wide angle and telephoto. Most point-and-shoot cameras have a fixed-aperture lens.
In low-light situations you want to have a small aperture value in order to bring in as much light as possible. The down-side to the smaller aperture values is the slower shutter speed. With a slow shutter speed, it takes longer to process the picture, therefore, any movement by the subjects or in the camera will cause blurring. On the other hand, a larger aperture value carries with it a faster shutter speed. This allows you to take action pictures.
Changing the aperture also changes the depth of field. The depth of field refers to the depth of a picture from foreground to background and what will appear sharp in the picture. The depth of field is increased with a smaller aperture value. This works well with pictures such as landscapes. The depth of field is then decreased with a larger aperture value. Portraits are best taken with decreased depth of field so that the sharpness of the picture is focused on the subject and not the background.
Exposure - Auto or Manual?
One of the most important aspects of photography is exposure control. Conrolling the exposure ensures that the darkest parts of the picture stay dark and the lightest parts stay light.
When a camera uses autoexposure, middle gray is used as the average brightness even though the brightness of the image is darker or lighter. This causes the picture to be too dark or too light. Controlling the exposure eliminates the guess of autoexposure and finds the true brightness of the image. Autoexposure does work well with images that are in bright sunlight, in diffused light, or evenly lit indoors situations.
Lightening or darkening a picture can be manually done using exposure compensation. Increasing the exposure lightens the picture and decreasing the exposure darkens it. Increasing and decreasing the exposure is measured in "stops".
When you adjust exposure compensation you can do so in full stops and even finer increments - usually one-third (shown here) or one-half stops. On most cameras you will see a scale displayed when you use this command. The "0" indicates the exposure suggested by the camera. As you adjust the exposure toward the plus (+) side of the scale the image gets lighter. As you adjust it toward the minus (-) side it gets darker. Here you see the results as it's adjusted from +2 (left) to -2 (right). The effect of the changes on the image are dramatic.
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