Transparency (photography)
Encyclopedia
Photography
Photography is the art, science and practice of creating durable images by recording light or other electromagnetic radiation, either electronically by means of an image sensor or chemically by means of a light-sensitive material such as photographic film...
, a reversal film is a type of photographic film
Photographic film
Photographic film is a sheet of plastic coated with an emulsion containing light-sensitive silver halide salts with variable crystal sizes that determine the sensitivity, contrast and resolution of the film...
that produces a positive image on a transparent base. Also known as dias or slide. The film is processed to produce transparencies or diapositives instead of negatives
Negative (photography)
In photography, a negative may refer to three different things, although they are all related.-A negative:Film for 35 mm cameras comes in long narrow strips of chemical-coated plastic or cellulose acetate. As each image is captured by the camera onto the film strip, the film strip advances so that...
and prints
Photographic printing
Photographic printing is the process of producing a final image on paper for viewing, using chemically sensitized paper. The paper is exposed to a photographic negative, a positive transparency , or a digital image file projected using an enlarger or digital exposure unit such as a LightJet printer...
. Reversal film is produced in various sizes, from 35mm
135 film
The term 135 was introduced by Kodak in 1934 as a designation for cartridge film wide, specifically for still photography. It quickly grew in popularity, surpassing 120 film by the late 1960s to become the most popular photographic film format...
roll film
Roll film
Rollfilm or roll film is any type of spool-wound photographic film protected from white light exposure by a paper backing, as opposed to film which is protected from exposure and wound forward in a cartridge. Confusingly, roll film was originally often referred to as "cartridge" film because of its...
to 8×10" sheet film
Sheet film
Sheet film is large format and medium format photographic film supplied on individual sheets of acetate or polyester film base rather than rolls. Sheet film was initially supplied as an alternative to glass plates...
.
A slide is a specially mounted individual transparency intended for projection onto a screen using a slide projector
Slide projector
A slide projector is an opto-mechanical device to view photographic slides. Slide projectors were common in the 1950s to the 1970s as a form of entertainment; family members and friends would gather to view slide shows...
. This allows the photograph to be viewed by a large audience at once. The most common form is the 35mm slide, with the image framed in a 2×2" cardboard or plastic mount. Some specialized labs produce slides from digital camera images in formats such as JPEG
JPEG
In computing, JPEG . The degree of compression can be adjusted, allowing a selectable tradeoff between storage size and image quality. JPEG typically achieves 10:1 compression with little perceptible loss in image quality....
, and also work with computer-generated presentation graphics and make slides from images such as fingerprints, microscopic sections, paper documents, astronomical images, etc.
Reversal film is sometimes used as motion picture film, mostly in the 16mm, Super 8
Super 8 mm film
Super 8 mm film is a motion picture film format released in 1965 by Eastman Kodak as an improvement of the older "Double" or "Regular" 8 mm home movie format....
and 8mm formats, to yield a positive image on the camera original. This avoids the expense and slight degradation of image quality resulting from using a negative film, and copying to a positive, to produce a print for projection.
Additive methods
The earliest practical and commercially successful color photographyColor photography
Color photography is photography that uses media capable of representing colors, which are traditionally produced chemically during the photographic processing phase...
reversal process was the Lumière
Lumière
-Characters:*Lumière , one of the two main characters of the 2002 anime series Kiddy Grade*Lumiere, a character in the Disney version of Beauty and the Beast-Places:*Lumière, a restaurant in Vancouver, Canada...
Autochrome
Autochrome Lumière
The Autochrome Lumière is an early color photography process. Patented in 1903 by the Lumière brothers in France and first marketed in 1907, it was the principal color photography process in use before the advent of subtractive color film in the mid-1930s....
, introduced in 1907. This was an additive
Additive color
An additive color model involves light emitted directly from a source or illuminant of some sort. The additive reproduction process usually uses red, green and blue light to produce the other colors. Combining one of these additive primary colors with another in equal amounts produces the...
method, using a panchromatic
Panchromatic
Panchromatic film is a type of black-and-white photographic film that is sensitive to all wavelengths of visible light. A panchromatic film therefore produces a realistic reproduction of a scene as it appears to the human eye. Almost all modern photographic film is panchromatic, but some types are...
emulsion coated on a thin glass plate previously coated with a layer of dyed potato starch
Potato starch
Potato starch is starch extracted from potatoes. The cells of the root tubers of the potato plant contain starch grains . To extract the starch, the potatoes are crushed; the starch grains are released from the destroyed cells...
grains. Autochrome plates were discontinued in the 1930s after the introduction of Lumière Filmcolor in sheet film
Sheet film
Sheet film is large format and medium format photographic film supplied on individual sheets of acetate or polyester film base rather than rolls. Sheet film was initially supplied as an alternative to glass plates...
and Lumicolor in roll film
Roll film
Rollfilm or roll film is any type of spool-wound photographic film protected from white light exposure by a paper backing, as opposed to film which is protected from exposure and wound forward in a cartridge. Confusingly, roll film was originally often referred to as "cartridge" film because of its...
sizes. Also using the additive principle and reversal processing were the Agfa color screen plates and films and Dufaycolor
Dufaycolor
Dufaycolor is an early French and British additive color photographic film process for motion pictures and stills photography. It was based on a four-color screen photographic process invented in 1908 by Frenchman Louis Dufay...
film, all of which were discontinued by 1961.
Subtractive methods
Leopold Godowsky, Jr.Leopold Godowsky, Jr.
Leopold Godowsky, Jr. was an American violinist and chemist, who together with Leopold Mannes created the first practical color transparency film, Kodachrome.-Beginning:...
and Leopold Mannes
Leopold Mannes
Leopold Damrosch Mannes was a Jewish-American musician, born in New York City, who, together with Leopold Godowsky, Jr., created the first practical color transparency film, Kodachrome....
, working with the Eastman Kodak Company
Eastman Kodak
Eastman Kodak Company is a multinational imaging and photographic equipment, materials and services company headquarted in Rochester, New York, United States. It was founded by George Eastman in 1892....
, developed Kodachrome
Kodachrome
Kodachrome is the trademarked brand name of a type of color reversal film that was manufactured by Eastman Kodak from 1935 to 2009.-Background:...
, the first commercially successful color film to use the subtractive
Subtractive color
A subtractive color model explains the mixing of paints, dyes, inks, and natural colorants to create a full range of colors, each caused by subtracting some wavelengths of light and reflecting the others...
method. Kodachrome was introduced in 1935 as 16mm motion picture film, and in 1936 as 35mm
135 film
The term 135 was introduced by Kodak in 1934 as a designation for cartridge film wide, specifically for still photography. It quickly grew in popularity, surpassing 120 film by the late 1960s to become the most popular photographic film format...
film for still cameras. The Kodachrome films contained no color dye couplers; these were added during processing.
In late 1936, Agafacolor Neu
Agfacolor
thumb|An Agfacolor slide dating from the early 1940s. While the colors themselves hold up well after 60 years, damages visible include dust and [[Newton's rings]].Agfacolor is a series of color photographic products produced by Agfa of Germany...
was launched, Agfa having overcome earlier difficulties with color sensitivity problems. This film had the dye couplers incorporated into the emulsion, making processing simpler than for Kodachrome.
Early color negative film
Color print film
Color print film is the most common type of photographic film in consumer use. Print film produces a negative image when it is developed, requiring it to be reversed again when it is printed on to photographic paper....
had many shortcomings, including the high cost of the film, processing and printing, the mediocre color quality, rapid fading and discoloration of highlights of some types of print that became noticeable after several years. Amateurs who owned projection equipment used reversal films extensively because the cost of projection equipment and slide film was offset by not having to pay for prints. Eventually, print quality improved and prices decreased, and, by the 1970s, color negative film and color prints had largely displaced slides as the primary method of amateur photography.
Until about 1995, color transparency was preferred for publication, and was widely used in commercial and advertising
Advertising
Advertising is a form of communication used to persuade an audience to take some action with respect to products, ideas, or services. Most commonly, the desired result is to drive consumer behavior with respect to a commercial offering, although political and ideological advertising is also common...
photography, reportage, sports, stock and nature photography. Digital
Digital
A digital system is a data technology that uses discrete values. By contrast, non-digital systems use a continuous range of values to represent information...
media gradually replaced transparency film.
Film types
All color reversal film sold today is developed with the E-6 processE-6 process
The E-6 process is a chromogenic photographic process for developing Ektachrome, Fujichrome and other color reversal photographic film....
. The non-substantive Kodachrome
Kodachrome
Kodachrome is the trademarked brand name of a type of color reversal film that was manufactured by Eastman Kodak from 1935 to 2009.-Background:...
films, the last of which was discontinued in 2009, was processed with the K-14 process
K-14 process
K-14 was the developing process for Kodak's Kodachrome transparency film; the last version having been designated Process K-14M. The process differed significantly from its contemporary, the E-6 process, in both complexity and length. Kodachrome film has no integral color couplers; dyes are...
.
Polaroid
Polaroid Corporation
Polaroid Corporation is an American-based international consumer electronics and eyewear company, originally founded in 1937 by Edwin H. Land. It is most famous for its instant film cameras, which reached the market in 1948, and continued to be the company's flagship product line until the February...
produced an instant
Instant film
Instant film is a type of photographic film first introduced by Polaroid that is designed to be used in an instant camera...
slide film called Polachrome. It was packaged in cassettes like normal 35mm
135 film
The term 135 was introduced by Kodak in 1934 as a designation for cartridge film wide, specifically for still photography. It quickly grew in popularity, surpassing 120 film by the late 1960s to become the most popular photographic film format...
film. A separate processing unit was used to develop it after exposure.
Black and white
Black-and-white transparencies can be made directly with some modern black-and-whiteBlack-and-white
Black-and-white, often abbreviated B/W or B&W, is a term referring to a number of monochrome forms in visual arts.Black-and-white as a description is also something of a misnomer, for in addition to black and white, most of these media included varying shades of gray...
film using reversal processing
Photographic developer
In the processing of photographic films, plates or papers, the photographic developer is a chemical that makes the latent image on the film or print visible. It does this by reducing the silver halides that have been exposed to light to elemental silver in the gelatine matrix...
. The process is used when transparencies are desired rather than the negatives normally yielded by these films. First, the negative image is developed but the undeveloped silver halide salts are not removed by fixing. The negative image is removed by bleaching with a solution of potassium permanganate
Potassium permanganate
Potassium permanganate is an inorganic chemical compound with the formula KMnO4. It is a salt consisting of K+ and MnO4− ions. Formerly known as permanganate of potash or Condy's crystals, it is a strong oxidizing agent. It dissolves in water to give intensely purple solutions, the...
or potassium dichromate in dilute (typically, one percent) sulfuric acid
Sulfuric acid
Sulfuric acid is a strong mineral acid with the molecular formula . Its historical name is oil of vitriol. Pure sulfuric acid is a highly corrosive, colorless, viscous liquid. The salts of sulfuric acid are called sulfates...
, which is removed by washing
Washing (photography)
In photography, washing is an important part of all film processing and printmaking processes. After materials have been fixed, washing removes unwanted and exhausted processing chemicals which, if left in situ, may cause deterioration and destruction of the image.A disadvantage of the use of...
and a clearing bath containing sodium metabisulfite
Sodium metabisulfite
Sodium metabisulfite or sodium pyrosulfite is an inorganic compound of chemical formula Na2S2O5. The substance is sometimes referred to as disodium...
or potassium metabisulfite
Potassium metabisulfite
Potassium metabisulfite, K2S2O5, also known as potassium pyrosulfite, is a white crystalline powder with a pungent sulfur odour. The main use for the chemical is as an antioxidant or chemical sterilant. It is a disulfite and is chemically very similar to sodium metabisulfite, with which it is...
. The remaining silver halide salts are re-exposed to light, developed and fixed (the fixing bath mainly serves to harden the gelatin, as no undeveloped silver salts should still remain), and the film is washed and dried.
Black-and-white transparencies were once popular for presentation of lecture materials using 3"
Inch
An inch is the name of a unit of length in a number of different systems, including Imperial units, and United States customary units. There are 36 inches in a yard and 12 inches in a foot...
by 4" (3" square in the UK) glass-mounted slides. Such positive black-and-white projection is now rarely done, except in motion pictures. Even where black-and-white positives are currently used, the process to create them typically uses an internegative with standard processing instead of a chemical reversal process.
Black-and-white reversal films are less common than color reversal films.
Black-and-white reversal processing needs have changed over the 100+ years it has been around. Today the debate is widespread. Some require a better more optimal image to scan. Some are going back to old-time processes and require a positive to eliminate an entire step. Some want the better tonal quality a transparency
Transparency (projection)
A transparency, also known in industrial settings as a "viewfoil" or "foil", is a thin sheet of transparent flexible material, typically cellulose acetate, onto which figures can be drawn. These are then placed on an overhead projector for display to an audience...
offers. Some just want to get out the slide projector.
- Agfa-GevaertAgfa-GevaertAgfa-Gevaert N.V. is a European multinational corporation that develops, manufactures, and distributes analogue and digital imaging products and systems, as well as IT solutions. The company has three divisions. Agfa Graphics offers integrated prepress and industrial inkjet systems to the...
discontinued its Agfa Scala 200x Professional black-and-white reversal film. This could be developed with their proprietary Scala process.
- The Foma company of the Czech RepublicCzech RepublicThe Czech Republic is a landlocked country in Central Europe. The country is bordered by Poland to the northeast, Slovakia to the east, Austria to the south, and Germany to the west and northwest....
produces the only remaining dedicated black-and-white reversal film for 35 mm stills, Fomapan R 100, which is also available in movie filmFilm stockFilm stock is photographic film on which filmmaking of motion pictures are shot and reproduced. The equivalent in television production is video tape.-1889–1899:...
formats.
- Kodak & Foma currently produce kits for reversal processing.
- dr5 Chrome process.
- Kodak Tri-X Reversal Film 7266 and Kodak Plus-X Reversal Film 7265 are black-and-white reversal films used for movie making.
Uses
Reversal films are the preferred film choice of professional photographers for images intended for reproduction in print media. This is because of the films' high contrast and high image resolution compared to negative (print) films.Displaying images
Finished transparencies are most frequently displayed by projection. Some projectors use a sliding mechanism to manually pull the transparency out of the side of the machine, where it is replaced by the next image. Modern, advanced projectors typically use a carousel that holds a large number of slides; a mechanism automatically pulls a single slide from the carousel and places it in front of the lamp.Small externally lit or battery-powered magnifying viewers are available.
External links
- Kodak TRI-X Reversal Film 7266
- Ilford B&W reversal processing description
- Ilford B&W reversal processing PDF manual
- dr5CHROME (B&W reversal)
- Color Reversal Film Information and Comparison Chart