Telecentric lenses collimate light passing through them, eliminating perspective distortion and providing a fixed magnification independent of working distance.  They are generally very low distortion and offer superior depth of focus than general purpose lenses.  Most telecentric lenses have a fixed working distance and often have no moving parts making them ideal for industrial applications where unwanted adjustments could cause problems.  Telecentric lenses are generally used for high precision measurements or in applications when perspective issues demand them

Although Telecentric lenses are available in a variety of formats, by far the most common mount type is C-mount.  This is because telecentric lenses, by their nature need to be the same physical size as the object (so that collimation can be achieved).

They can be used with extension tubes to optimise coverage and working distance

High resolution, versions give superior optical performance to standard resolution models and there are now several grades of telecentric lenses allowing full resolving power for very small pixel sizes and high pixel counts.

These lenses are generally optimised for use in the visible spectrum but some models are also IR corrected.

C-mount telecentric lenses may also be used on CS-mount cameras with the use of a 5mm spacer between the camera and the lens.