Formula to calculate focal length for c-mount lenses ?
Every c-mount lens has a 'specification' associated with it which determines
if it is suitable for a given application. One of the most important is the
focal length of the lens as this determines the field of view. The field of
view is typically the size of the object you want to see with the camera. To
calculate the focal length of a lens you need to know certain information
about the application;
CCD(V) =
FOV =
WD =
sensor size (vertical)
object height
working distance from object to front of lens
If you know these three basic measurements then you can calculate the focal
length of the lens you require for your application.
Focal Length = (WD x CCD(V)) / FOV
Having established the focal length it is then important to consider other
aspects of the lens 'specification' such as minimum working distance,
resolution and resolving power.
There are hundreds of lenses to choose from so please give Multipix a call to
discuss your application so we can offer further advice.
NOTE: Here are some common sensor sizes and the associated vertical measurements.
