Most point-and-shoot cameras don't let you control the shutter speed or aperture.
A fixed-speed camera is one that does not allow you to change the speed setting on the camera. Fixed-speed cameras are more commonly known as point-and-shoot cameras or compact cameras, and they are available in both film and digital models. These cameras make it easy for you to take pictures, but the disadvantage of fixed-speed cameras is that you lose creative control of the process and have limited exposure options.
Manual Control
Fixed-speed cameras are suitable if you are taking snapshots of friends or doing some basic landscape photography. But most completely lack manual controls, especially disposable cameras and low-end point-and-shoot cameras. Better-quality compact cameras usually have a setting for the ISO speed, which is equivalent to choosing a film that is more sensitive to light. ISO settings have become a standard measurement of a camera's sensitivity to light and is used even with digital cameras. A lack of manual control means that you have no choice on the shutter speed, the aperture, or flash intensity, and some fixed-speed cameras won't allow you to turn off the flash.
Depth-of-Field Adjustment
Depth of field is the distance over which a camera can produce a sharp image. On professional cameras, you can control this with a combination of aperture and shutter speed, but a fixed-speed camera doesn't let you have any creative control over your depth of field. These cameras are usually designed to get the best possible focus over a wide range of distances from the camera, usually between a couple of feet and infinity. This means that if you are photographing a flower that's close to your camera, both the flower and the distant background will be rendered as sharply as possible. Sometimes, you may not want the background in sharp focus because it will detract from your subject.
Image Quality
Your camera's resolution determines how well it can render fine details in your finished image. Digital cameras, including fixed-speed cameras, use megapixels as a measurement of resolution. A higher megapixel means more digital information in the image which translates into better detail. In film fixed-speed cameras, a lower ISO rating on your film will give you a finer-grained negative and yield an image with better details than a film with a high ISO setting. Because fixed-speed cameras are usually low-end products, the megapixel rating on them is usually less than that of better-quality cameras. This means that you will probably get acceptable photographs if you intend to print them as 4-by-6 inch images or post them on the Web, but for larger prints like 8-by-10 inch images, you'll start to loose image quality.
Moving Subjects
Because fixed-speed cameras don't allow you to change the shutter speed, you're generally limited to subjects that aren't moving or that are moving slowly. Choosing a high ISO number, such as ISO 400, makes your camera less responsive in low-light situations, but it is better for photographing moving subjects. But changing the ISO settings still can't give you the creative options of a camera with full manual controls. A slower shutter speed can let you creatively blur motion, such as a waterfall or moving carnival ride. A higher shutter speed can stop action, such as a baseball player in the act of catching a ball.
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