Free Tools, Utilities, and Helpful Information

Please feel free to use the following tools and information to help you in your machine vision needs.

Tools & Utilities

This free utility performs conversions between different units in over 20 categories. Very useful for converting from English units to metric and vice versa.

Lens & Sensor

Back Flange Distance – The distance from the mount face plane to the image detector plane. Each mount has its own specification. This data is useful for optical designs.

Lens Type
Back Focal Distance
C mount 17.526 mm = 0.690 inches Standard for CCD cameras
CS Mount 12.5 mm = 0.492 inches Alternate standard for CCD cameras, especially those with small sensor arrays.
F-Mount 1.831 inches Nikon 35mm SLR
2/3 inch Bayonet mount 48 mm This is normally called “B4 mount” or “Bayonet
1/2 inch Bayonet mount – general 35.74 mm Various manufacturers, except Sony, use this mount (usually called general mount).
1/2 inch Bayonet mount – SONY 38 mm Sony uses this mount (usually called “Sony mount” or “38-mount”).

*When you want to use a C-mount lens on a CS-mount camera, you should use a 5mm thick CS-C mount adapter.

Similar adapters are available from C-mount to F-mount (Nikon) lenses.

Image Diagonals – Active image area on various sized CCD arrays.

Sensor Size
Array Size
1/4″ chip 2.7 x 3.7 mm 4.6 mm
1/3″ chip 4.8 x 3.6 mm 6.0 mm
1/2″ chip 6.4 x 4.8 mm 8.0 mm
2/3″ chip 8.8 x 6.6 mm 11.0 mm
1″ chip 12.7 x 9.525 mm 15.9 mm

Lenses for these chip sizes are actually designed to fill only this size array. Note that a 1″ chip only fills a 15.9 mm array size, which is about 5/8″. You can use a lens designed for a larger chip on a smaller chip. For example, you could use a lens designed for a 2/3″ chip (often called a 2/3″ lens” on a camera with a 1/2 ” array. F-mount lenses are designed to fill a 35 mm diagonal array.