Flange focal distance

Property of a lens mount system

For an interchangeable lens camera, the flange focal distance (FFD) of a lens mount system is the distance from the mounting flange to the film or image sensor plane. This value is different for different camera systems. The range of this distance, which will render an image clearly in focus within all focal lengths, is usually measured to a precision of hundredths of millimetres, and is not to be confused with depth of field.

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