In photography there are many important elements that impact the way a picture looks. Exposure, film speed, camera quality and composition all make a difference. But one of the most important elements, contrast, can be easily manipulated and - when used properly- can take your image to a whole new level.
In simple terms, contrast is the difference between the lights and the darks in your picture. In terms of black and white photography, high contrast prints have very dark black and super bright whites with no shades in between, while low contrast images will have more grey. In color photographs, contrast can be used to describe the intensity of the colors and how they stand out in relation to each other. While there is no "ideal" level of contrast in an image, a good rule is to focus on creating images that have pure black, pure white and every tone in between. However, this is more difficult than it may seem!
Contrast in Action
As a photographer, you'll probably find a set amount of contrast that works for you. Some prefer high contrast, some prefer low, but remember that it's all about what works for you. As long as your pictures tell the story you want to share, there is no right or wrong answer.
If you want to see an example of excellent normal contrast, take a look at the photographs of Ansel Adams. His landscape photographs in black and white cover every base possible in terms of greys, blacks, and whites, and are quite powerful because of it. As an example of high contrast, films like Sin City and The Spirit used high contrast imagery to tell their story.
Manipulating Contrast
There are a few things you can do to adjust the contrast of your images. Different kinds of film or digital settings will result in images with a higher or lower contrast (for instance, slide film has a high contrast ratio compared to regular film). You can also increase the time your film develops or "push" your film so that your images will have more contrast. Be careful not to over-develop your film; while you can always make new prints your actual shot film is irreplaceable and cannot be fixed after you break it.
In the darkroom, you can put a filter on your enlarger to change the contrast of your prints. A #1 filter will be a slight contrast bump, whereas a #4 filter will dramatically increase the level of contrast in the final image. If you're using a digital camera, most photo editing software has a built in contrast option that will let you mimic the changes you could make in the darkroom. Contrast is unlimited in what you can do with it so play around and take it to the limit and see what happens.
The amount of contrast in your picture can also impact what the viewer sees. It can help further define important parts of your photograph as well as create a higher quality image when done properly. Use the "pure white, pure black" rule in every picture and you'll see a huge difference in the prints you will produce. Once you understand what degree of contrast works in your photos, you'll start to see how you can use contrast in the real world to shoot even better pictures. Like anything in life, the best way to get better is to practice and take more pictures!