Please note: All calculations are based on theoretical formulas only, assuming the principal planes are identical. Actual results will differ! Our sales team will be happy to assist you!


Focal Length Calculator

With this tool you can calculate the required focal length to take a picture of an object at a given distance in order to generate an image fitting on your sensor size.

Object size:    mm
Image size:    mm
Object distance:    m
Magnification:    x
Focal length:    mm
Angle of view:    °
focal length calculator


Of course, all distances are measured from the lens front and rear principal points respectively. Too often, unfortunately, these points are not specified by the lens manufacturer: it's hard to guess their position, since they can be anywhere inside or outside the lens. Anyway, the rear principal point is always one focal length ahead the sensor * when the lens is focused at infinity. The location of the front principal point cannot be neglected when using macro lenses.

 

Depth of field calculators

This page is useful to calculate the depth of field when using a given lens or to choose the required aperture in order to achieve a given depth of field.

The circle of confusion c is the diameter of a circle on the image plane that can be considered a single point when the image is observed (the size of the film/imager is different that the size of the print/screen. For 35 mm photography c is usually 0.025 mm, but this value depends of course on the size of the final prints.

The hyperfocal distance H is the minimum distance from the front principal plane that will appear sharp when the lens is focuses at infinity (xo = infinity).

Calculator for finding the depth of field
for a given lens and aperture.

Focal length: f =   mm
Aperture: N =  f / 
Object distance: xo =   m
Circle of confusion: c =   mm
Hyperfocal distance: H =   m
Far depth of field: Df =   m
Near depth of field: Dn =   m
Depth of field: D =   m
 

Calculator for finding the required aperture
for a given depth of field and a given lens.

Focal length: f =   mm
Far depth of field: Df =   m
Near depth of field: Dn =   m
Circle of confusion: c =   mm
Aperture: N =  f / 
Object (focus) distance: xo =   m
Hyperfocal distance: H =   m

The maximum possible depth of field is obtained when the lens is focused one focal length f farther than the hyperfocal distance H: everything between Dn and infinity will be sharp. The value "Infinity" can be entered for Df, but since it's case sensitive it has to be typed as shown.