Large Format Photography
Lenses - Focal Length and Coverage:
|All camera lenses for all formats
have a focal length -
It is the measurement of the distance from the lens to the film when focused at infinity in millimeters or inches.
this is the "burning ants" distance
Measure your magnifying
glass focal length by focusing a distant light source on any surface and
measuring that distance.
Lens Focal Length - _____________________mm ______________________ inches
The f/stop or aperture is determined by the size of the lens opening in relation to its focal length.
First measure the focal length of your lens._________________mm ______________inches
The size of your lens diameter: __________________mm ___________________inches
The f/stop is the
focal length divided by the diameter of the lens (or lens opening).
Angle of view:
The angle of view
is determined by the focal length AND the size of the film format.
The "Normal" lens with about a 45 degree angle of view has a focal length equal or close to the diagonal measurement of the film. Normal for 35mm is 50mm, normal for 4x5 is 150mm
A lens that is less
than the "normal" focal length will give you a wide angle view.
pinhole cameras have a pinhole that is .5 millimeter (one half millimeter.
The f/stop will change with changes in the distance