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Depth of Field in Portraits

            (Definition) Depth of field is the distance between nearest and farthest part of the subject which can be brought to acceptable focus on the film at the same time.

 

In portrait photography we are usually concerned with obtaining minimum depth of field.

 

Minimum depth of field is obtained when:

*   f number is tiny eg f2.8

*   Focal length is long

*   Subject is close


 

Shutter Speeds and Apertures

A clear understanding of the doubling and halving relationship between f-stops and shutter speeds is fundamental to understanding exposure and making the correct choice.

 

Each time you click from one f stop to another, you are changing the size of the hole through which the light passes.

Example: When you click from f5.6 to f4 you are doubling the quantity of light reaching the film (assuming no other changes are made).


With standard shutter speeds, when you click from one shutter speed to another, you are altering the length of time during which the film is exposed.

Example: When you rotate your shutter speed dial from 1/125 second to 1/500 second you are halving the quantity of light reaching the film.