Photo Glossary

Offset lithography

It is the printing method that uses to produce high volumes of magazines, catalogues and newspaper.

Opacity

The density of a material such as a film or filter.

Opening up

It is increasing the size of the lens aperture or decreasing the shutter speed to admit more light to the film.

Optical axis

A line through the optical center of a lens and perpendicular to the plane of its diameters.

Optical bench

It is a device for measuring the optical performance of lenses.

Optical glass

It is used for manufacturing lenses and prisms.

Optical sensitizing

It is a method of increasing a films sensitivity by the use of dyes.

Optical viewfinder

The small window in the camera that you look through when taking a picture.

Optical zoom

A lens that can be adjusted from one focal length to another.

Orthochromatic

Denotes film sensitive to blue and green light.

OTF

Off the Film. A meter reading that measures light reflected from the surface of the film during exposure.

Overexposure

Light sensitive material that has been exposed to more light.