Contrast in black and white photography

In a black-and-white photograph, contrast is defined as the difference in brightness from one part of the negative and print to another.

The measured brightness ratio difference between the lightest and darkest portion of an image is expressed as a ratio of f-stops, such as a 7:1 brightness ratio.
 

Scale is also a term used to describe tonal contrast range.

• Short-scale black-and-white negatives are those containing relatively few distinct gray tones from the darkest to lightest portions of the image.

• Long-scale black-and-white negatives contain many discernible individual tones of gray between the darkest and lightest parts of the negative.
   

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