Photographic Film and Sensitized Materials

Study Notes

Consists of an emulsion, which contains silver halides suspended in gelatin, coated on a transparent or reflective support.
The emulsion is the light-sensitive portion of the material.
Photographic film is a light-sensitive surface that captures images.
Photographic film contains silver halide grains suspended in animal gelatin and coated with celluloid materials.
It is composed of an emulsion, a gray or anti-halation backing, and a base.
The emulsion layer contains light-sensitive silver halide crystals evenly distributed in a plastic base material.
Gelatin in the emulsion holds the crystals together.
The anti-halation backing prevents light reflection from the base, which creates halos in images.
The base provides support for the emulsion and is typically made of plastic material.

35mm film is the most widely used format, known for its versatility and accessibility.
120 film is used in medium-format cameras, known for its higher resolution and larger negatives.
4x5 film is a large-format film used in specialized cameras, known for its exceptional image quality and artistic expression.

Black and white film is typically indicated with "Pan" or "Ortho" prefixes or suffixes and is used in black and white photography.
Colored film is divided into two types: negative and reversal.
Negative colored film is the most common type of colored film, used in general photography. It is relatively inexpensive and processed at standard photo labs.
Reversal colored film, also known as slide film, produces high-quality images but is more expensive and less-versatile than negative film. It provides vibrant colors and is often used for artistic purposes and requires precise exposure settings for optimal results. It is processed using the E-6 process.

Monochromatic film is sensitive to a single color of light, used for black and white photography.
- Blue sensitive film is specially treated to be more sensitive to blue light rays.
- Ultra-Violet sensitive film is suitable for ultraviolet photography.
Panchromatic film is sensitive to ultraviolet rays and all colors, particularly blue and violet.
Orthochromatic film is sensitive to all colors except red, also known as Kodalith Film.
Infrared film is sensitive to infrared and ultraviolet radiation.
X-Ray film is sensitive to the x-ray region of the electromagnetic spectrum.

Refers to the sensitivity of the film to light, or how easily the emulsion is affected by light.
It is measured by the American Standard Association (ASA), Deutsche Industrie Normen (DIN), or International Standard Organization (ISO).
ASA speed is expressed in an arithmetical value, where higher numbers indicate greater sensitivity.
DIN speed is expressed in a logarithmic value, where an increase of 3 degrees doubles the sensitivity of the film.
ISO speed uses both arithmetical and logarithmic values.
A higher ISO number indicates greater sensitivity to light, allowing for photography in low light conditions.

The structure of color film is similar to black and white film, with the exception that the emulsion layer is composed of three layers stacked on top of each other.
The top layer is sensitive only to blue light, allowing green and red light to pass through without exposure.
A yellow filter (Carey Lea Silver) is coated between the top and second layer to absorb any penetrating blue light but freely passes green and red light.
The middle layer is orthochromatic, sensitive to blue and green light, but not red light.
The bottom layer is panchromatic, sensitive to all colors.