Many photographers specialize in black and white photography due to its sheer power, elegance and beauty. However, it is important to note that black and white photography is not simply color photography with black and white film (or a black and white digital setting). Black and white photography has its own set of rules that it needs to abide by. Black and white photography, since it is colorless, needs to find other ways to set moods.
Tones are the most important element of black and white photography. As humans we don't really think about the world in tonal ranges. For us when we see light blue and then we look else where and see yellow, we are in fact seeing two different colors. However, when you take a black and white photograph with light blue and yellow in the same frame, the camera may not actually communicate the difference to your viewers since the colors have almost the exact same grey tone.
Therefore as a black and white photographer you have the extra responsibility to think about how the world looks in tones. You need to think about the whiteness of whites and the darkness of darks (known as tonal range). You need to see colors as tones, and your shadows will not become more intimate parts of your photographs. Likewise, you can use colors to help draw emphasis to a subject or idea anymore, now you will need to find other ways to draw emphasis to the main subject or smaller details within the photograph.
For great black and white photos you also must understand tonal range.
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