One thing a lot of people complain about is that when they are trying to take pictures, they wind up with dark images and they aren't sure why. This happens a lot with product photography.
Many people figure that if their images are dark, they can always use photoshop to try to fix the light level later or create a fake white background. There are a couple of reason why this isn't the best way to solve the problem.
1. If your image is dark, it is underexposed. When a digital image is underexposed, the picture becomes full of "noise", that is the grainy, colorful particles that ruin the clarity and color of your image. Not what you want.
2. If your subject is underexposed and you create a white background around it using the paint tool, your subject will really look bad because the light on it doesn't match the brightness of the background.
One of the reasons many people wind up with dark images is they don't understand how a light meter functions on their camera. Basically, a camera captures light. When you point your camera at a subject there can be light with all different varying degrees of brightness. Your camera, set on Auto mode, will try to let in enough light to match the amount of light that would be reflected off of something that was nuetral gray.
What does that mean? It means that no matter what you are taking a picture of, no matter what color it is, the camera wants to expose the picture with an "average" amount of light reaching the sensor. Not too bright, not too dark. Gray. Not gray the color, think intensity of light.
Have you ever taken a photo in the wintertime on a bright, sunny day of snow? What color was the snow when you opened the photo on the computer? Probably gray. Why didn't the camera show the snow as white like your eyes saw it? Because to the camera, there was too much light. There wasn't an average amount of light, there was a lot of light, so it automatically underexposed the shot to get gray.
At the same time, if you point your camera at something all dark or black, you will not get black in the final image, you will get gray. The camera will automatically OVERexpose to compensate.
A lot of times I see people talk about using a light box to photograph products such as jewelry and in theory this is a good idea. But, without knowledge of how to properly expose a photo, the lightbox in itself won't help. If the person shoots their product against a very bright background, like a white cloth, the camera is STILL going to underexpose the shot.
To get the best results, you need to compensate for what your camera will try to do automatically. You do this by setting your camera to M mode, Manual, and controlling your shutter speed and aperture to allow exactly the amount of light that you want.
Tomorrow's entry, I will talk about how to use manual mode with a typical point and shoot camera that makes it easy for you to take better pictures under any lighting conditions.