Enlarger
Encyclopedia
An enlarger is a specialized transparency projector
used to produce photographic
prints from film or glass negatives
using the gelatin silver process, or from transparencies.
, a condenser
or translucent screen to provide even illumination, a holder for the negative or transparency, and a specialised lens for projection. The light passes through a film
holder, which holds the exposed and developed photographic negative or transparency.
Prints made with an enlarger are called enlargements. Typically, enlargers are used in a darkroom
, an enclosed space from which extraneous light may be excluded; some commercial enlargers have an integral dark box so that they can be used in a light-filled room.
A condenser enlarger consists of a light source, a condensing lens
, a holder for the negative and a projecting lens. The condenser provides even illumination to the negative beneath it.
A diffuser enlarger's light source is diffused
by translucent glass or plastic, providing even illumination for the film.
Condenser enlargers produce higher contrast
than diffusers because light is scattered from its path by the negative's image silver; this is called the Callier Effect. The condenser's increased contrast emphasises any negative defects, such as dirt and scratches, and image grain.
Diffuser enlargers produce an image of the same contrast as a contact print from the negative.
Dedicated color enlargers contain an adjustable filter mechanism between the light source and the negative, enabling the user to control the amount of cyan, magenta and yellow light reaching the negative. Other models have a drawer where cut filters can be inserted into the light path. These enlargers can also be used with variable-contrast monochrome papers.
Digital enlargers project an image from an LCD screen at the film plane
, to produce a photographic enlargement from a digital file.
A horizontal enlarger consists of a trestle, with the head mounted on crossbars between two or more posts for extra stability. A horizontal enlarger structure is used when high quality, large format enlargements are required such as when photographs are taken from aircraft for mapping and taxation purposes.
The parts of the enlarger include baseboard, enlarger head, elevation knob, filter holder, negative carrier, glass plate, focus knob, girder scale, timer, bellows, and housing lift.
, onto to a flat surface bearing the sensitized photographic paper
. By adjusting the ratio of distance from film to lens to the distance from lens to paper, various degrees of enlargement may be obtained, with the physical enlargement ratio limited only by the structure of the enlarger and the size of the paper. As the image size is changed it is also necessary to change the focus of the lens. Some enlargers, such as Leica's "Autofocus" enlargers, perform this automatically.
An easel
is used to hold the paper perfectly flat. Some easels are designed with adjustable overlapping flat steel "blades" to crop the image on the paper to the desired size while keeping an unexposed white border about the image. Paper is sometimes placed directly on the table or enlarger base, and held down flat with metal strips.
The enlargement is made by first focusing the image with the lamp on, the lens at maximum aperture and the easel empty, usually with the aid of a focus finder
. The lamp is turned off, or in some cases, shuttered by a light-tight mechanism.
The image is focussed by changing the distance between the lens and the film, achieved by adjusting the length of a light-tight bellows with a geared rack and pinion
mechanism.
The lens is set to its working aperture. Enlarging lenses have an optimum range of apertures which yield a sharp image from corner to corner, often around f8. The lens is normally set to this aperture and any color filtration dialed in, if making a color print or one on variable-contrast black-and-white paper.
The enlarger's lamp or shutter mechanism is controlled either by an electronic timer, or by the operator - who marks time with a clock, metronome or simply by counting seconds - shuttering or turning off the lamp when the exposure is complete.
The exposed paper can be processed immediately or placed in a light-tight container for later processing.
Digitally controlled commercial enlargers typically adjust exposure in steps known as printer point
s; twelve printer points makes a factor of two change in exposure.
control.
Rather than project directly from the film negative to the print paper, a digital image may first be captured from the negative. This allows the operator or computer to quickly determine adjustments to brightness, contrast, clipping, and other characteristics. The image is then rendered by passing light through the negative and a built-in computer controlled enlarger optically projects this image to the paper for final exposure.
As a byproduct of the process a Compact Disc
recording may be made of the digital images, although a subsequent print made from these may be quite inferior to an image made from the negative due to digitization noise and lack of dynamic range which are characteristics of the digitizing process.
For better images, the negatives may be reprinted using the same automated machine under operator selection of the print to be made.
For example, a 5 by 7 inch print intended for viewing in a scrapbook
at 18 inches may be unsuitable for enlargement as an 8 by 10 inch print to be hung on a hallway wall to be viewed at the same distance, but usable at a larger 5 by 7 feet (twelve times larger) on a billboard
to be viewed no closer than eighteen feet (twelve times more distant).
, who made high quality enlargers, stopped producing them in 2005, but still supports already sold models.
Manufacturers old and new include:
Image projector
An image projector is an optical device that projects an image onto a surface, commonly a projection screen.Most projectors creates an image by shining a light through a small transparent image, but some newer types of projectors can project the image directly, by using lasers...
used to produce photographic
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...
prints from film or glass 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...
using the gelatin silver process, or from transparencies.
Construction
All enlargers consist of a light source, normally an incandescent light bulbIncandescent light bulb
The incandescent light bulb, incandescent lamp or incandescent light globe makes light by heating a metal filament wire to a high temperature until it glows. The hot filament is protected from air by a glass bulb that is filled with inert gas or evacuated. In a halogen lamp, a chemical process...
, a condenser
Condenser (optics)
A Condenser is an optical lens which renders a divergent beam from a point source into a parallel beam illuminating an object. It is an essential part of any imaging device, such as microscopes, slide projectors, and telescopes...
or translucent screen to provide even illumination, a holder for the negative or transparency, and a specialised lens for projection. The light passes through a 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...
holder, which holds the exposed and developed photographic negative or transparency.
Prints made with an enlarger are called enlargements. Typically, enlargers are used in a darkroom
Darkroom
A darkroom is a room that can be made completely dark to allow the processing of light sensitive photographic materials, including photographic film and photographic paper. Darkrooms have been created and used since the inception of photography in the early 19th century...
, an enclosed space from which extraneous light may be excluded; some commercial enlargers have an integral dark box so that they can be used in a light-filled room.
Types of Enlarger
Lens (optics)
A lens is an optical device with perfect or approximate axial symmetry which transmits and refracts light, converging or diverging the beam. A simple lens consists of a single optical element...
, a holder for the negative and a projecting lens. The condenser provides even illumination to the negative beneath it.
A diffuser enlarger's light source is diffused
Photon diffusion
Photon diffusion is a situation where photons travel through a material without being absorbed, but rather undergoing repeated scattering events which change the direction of their path. The path of any given photon is then effectively a random walk...
by translucent glass or plastic, providing even illumination for the film.
Condenser enlargers produce higher contrast
Contrast (vision)
Contrast is the difference in visual properties that makes an object distinguishable from other objects and the background. In visual perception of the real world, contrast is determined by the difference in the color and brightness of the object and other objects within the same field of view...
than diffusers because light is scattered from its path by the negative's image silver; this is called the Callier Effect. The condenser's increased contrast emphasises any negative defects, such as dirt and scratches, and image grain.
Diffuser enlargers produce an image of the same contrast as a contact print from the negative.
Dedicated color enlargers contain an adjustable filter mechanism between the light source and the negative, enabling the user to control the amount of cyan, magenta and yellow light reaching the negative. Other models have a drawer where cut filters can be inserted into the light path. These enlargers can also be used with variable-contrast monochrome papers.
Digital enlargers project an image from an LCD screen at the film plane
Film plane
A film plane is the area inside any image taking device with a lens and a digital sensor or film; such as a camera. The film plane varies in distance from the lens focal point in each manufacturer...
, to produce a photographic enlargement from a digital file.
Enlarger physical arrangements
Most modern enlargers are vertically mounted with the head pointing downward and adjusted up or down to change the size of the image projected onto the enlarger's base, or a work table if the unit is mounted to the wall.A horizontal enlarger consists of a trestle, with the head mounted on crossbars between two or more posts for extra stability. A horizontal enlarger structure is used when high quality, large format enlargements are required such as when photographs are taken from aircraft for mapping and taxation purposes.
The parts of the enlarger include baseboard, enlarger head, elevation knob, filter holder, negative carrier, glass plate, focus knob, girder scale, timer, bellows, and housing lift.
Principles of operation
The image from the negative or transparency is projected through a lens fitted with an adjustable iris apertureAperture
In optics, an aperture is a hole or an opening through which light travels. More specifically, the aperture of an optical system is the opening that determines the cone angle of a bundle of rays that come to a focus in the image plane. The aperture determines how collimated the admitted rays are,...
, onto to a flat surface bearing the sensitized photographic paper
Photographic paper
Photographic paper is paper coated with light-sensitive chemicals, used for making photographic prints.Photographic paper is exposed to light in a controlled manner, either by placing a negative in contact with the paper directly to produce a contact print, by using an enlarger in order to create a...
. By adjusting the ratio of distance from film to lens to the distance from lens to paper, various degrees of enlargement may be obtained, with the physical enlargement ratio limited only by the structure of the enlarger and the size of the paper. As the image size is changed it is also necessary to change the focus of the lens. Some enlargers, such as Leica's "Autofocus" enlargers, perform this automatically.
An easel
Easel
An easel is an upright support used for displaying and/or fixing something resting upon it.-Etymology:The word is an old Germanic synonym for donkey...
is used to hold the paper perfectly flat. Some easels are designed with adjustable overlapping flat steel "blades" to crop the image on the paper to the desired size while keeping an unexposed white border about the image. Paper is sometimes placed directly on the table or enlarger base, and held down flat with metal strips.
The enlargement is made by first focusing the image with the lamp on, the lens at maximum aperture and the easel empty, usually with the aid of a focus finder
Focus finder
A focus finder is a simple optical tool used to examine a virtual image in an optical device to achieve a precise point of focus.They are most commonly used in photographic enlarging to ensure that the negative image is accurately focussed on the easel....
. The lamp is turned off, or in some cases, shuttered by a light-tight mechanism.
The image is focussed by changing the distance between the lens and the film, achieved by adjusting the length of a light-tight bellows with a geared rack and pinion
Rack and pinion
A rack and pinion is a type of linear actuator that comprises a pair of gears which convert rotational motion into linear motion. A circular gear called "the pinion" engages teeth on a linear "gear" bar called "the rack"; rotational motion applied to the pinion causes the rack to move, thereby...
mechanism.
The lens is set to its working aperture. Enlarging lenses have an optimum range of apertures which yield a sharp image from corner to corner, often around f8. The lens is normally set to this aperture and any color filtration dialed in, if making a color print or one on variable-contrast black-and-white paper.
The enlarger's lamp or shutter mechanism is controlled either by an electronic timer, or by the operator - who marks time with a clock, metronome or simply by counting seconds - shuttering or turning off the lamp when the exposure is complete.
The exposed paper can be processed immediately or placed in a light-tight container for later processing.
Digitally controlled commercial enlargers typically adjust exposure in steps known as printer point
Printer point
In photography, a printer point is a unit of relative exposure, in printing a negative, equal to a 1/12 of a stop or 0.025 Log unit of exposure ratio ....
s; twelve printer points makes a factor of two change in exposure.
Paper processing
After exposure, photographic paper is developed, fixed, washed and dried using the gelatin silver process.Automated print machines
Automated photo print machines have the same basic elements and integrate each of the steps outlined above in a single complex machine under operator and computerComputer
A computer is a programmable machine designed to sequentially and automatically carry out a sequence of arithmetic or logical operations. The particular sequence of operations can be changed readily, allowing the computer to solve more than one kind of problem...
control.
Rather than project directly from the film negative to the print paper, a digital image may first be captured from the negative. This allows the operator or computer to quickly determine adjustments to brightness, contrast, clipping, and other characteristics. The image is then rendered by passing light through the negative and a built-in computer controlled enlarger optically projects this image to the paper for final exposure.
As a byproduct of the process a Compact Disc
Compact Disc
The Compact Disc is an optical disc used to store digital data. It was originally developed to store and playback sound recordings exclusively, but later expanded to encompass data storage , write-once audio and data storage , rewritable media , Video Compact Discs , Super Video Compact Discs ,...
recording may be made of the digital images, although a subsequent print made from these may be quite inferior to an image made from the negative due to digitization noise and lack of dynamic range which are characteristics of the digitizing process.
For better images, the negatives may be reprinted using the same automated machine under operator selection of the print to be made.
Advantages
- The image may be printed to a size different from the negative or transparency. Without an enlarger, only a contact printContact printA contact print is a photographic image produced from film; sometimes from a film negative, and sometimes from a film positive. The defining characteristic of a contact print is that the photographic result is made by exposing through the film negative or positive, onto a light sensitive material...
would be possible, and large images would require large size negatives and hence very large cameras.
- Local contrast and density of various parts of the print can be easily controlled. Changing the amount of light exposing the paper in various areas will change the image density in those areas. A mask with a hole can be used to add extra light to an area "burning", which will have the effect of darkening the regions with additional exposure, while the use of a small wand to reduce the total exposure to a region is called "dodging"DodgingDodging and burning are terms used in photography for a technique used during the printing process to manipulate the exposure of a selected area on a photographic print, deviating from the rest of the image's exposure...
and has the effect of lightening the regions with reduced exposure. The tool is kept moving to avoid producing a sharp edge at the region boundary. Using these techniques it is possible to make significant changes to the mood or emphasis of a photographic print. Similar methods are available with contact printing, but it is more difficult to see the image as it is being manipulated.
- It is also possible to make composite photographs by overlaying the print with a hand-cut mask, performing an exposure, and then using the inverse of that mask to perform another exposure with a different negative. This is much more difficult to do well using photographic methods than it is now by using the methods of modern digital image manipulation.
Image enlargement limits
The practical amount of enlargement (irrespective of the enlarger structure) will depend upon the grain size of the negative, the sharpness (accuracy) of both the camera and projector lenses, blur in the image due to subject motion and camera shake during the exposure, and the intended viewing distance of the final product.For example, a 5 by 7 inch print intended for viewing in a scrapbook
Scrapbook (film)
Scrapbook is a horror film about a young woman who is kidnapped, held captive, and repeatedly beaten and raped for several days. The title refers to a scrapbook that her captor uses as a record of the ordeals of his victims.-Plot:...
at 18 inches may be unsuitable for enlargement as an 8 by 10 inch print to be hung on a hallway wall to be viewed at the same distance, but usable at a larger 5 by 7 feet (twelve times larger) on a billboard
Billboard
Billboard is a weekly American magazine devoted to the music industry, and is one of the oldest trade magazines in the world. It maintains several internationally recognized music charts that track the most popular songs and albums in various categories on a weekly basis...
to be viewed no closer than eighteen feet (twelve times more distant).
Manufacturers
Because of the change to digital, many manufacturers no longer make enlargers for the professional photographer. DurstDurst
Durst Phototechnik AG is a manufacturer of photographic and printing equipment, based in Brixen, Italy.-History:Established in 1936 by two brothers, Julius and Gilbert Durst, who were enthusiasts in the field of photography, encouraged by their mother, who was also a keen photographer and had her...
, who made high quality enlargers, stopped producing them in 2005, but still supports already sold models.
Manufacturers old and new include:
- Leitz
- DurstDurstDurst Phototechnik AG is a manufacturer of photographic and printing equipment, based in Brixen, Italy.-History:Established in 1936 by two brothers, Julius and Gilbert Durst, who were enthusiasts in the field of photography, encouraged by their mother, who was also a keen photographer and had her...
- Dunco
- MeoptaMeoptaMeopta is Czech-American global manufacturer of precision optics, specializing in the design, engineering and assembly of complex optical, opto-mechanical and opto-electronic systems. Meopta makes stuff for the consumer, industrial and military markets....
- BeselerCharles Beseler CompanyCharles Beseler Company is a Stroudsburg, Pennsylvania industrial company addressing four primary markets: public and corporate steel shelving and furniture, iron shelving and storage, shrink wrap packaging and silver halide photography...
- OmegaOmega (camera)Omega is the name of various medium-format cameras and enlargers. The Simmon Brothers, known for their line of enlargers, built the original Simmon Omega cameras in the United States. These rangefinder cameras took 6x7cm photographs on 120 roll film. Later, Konica manufactured the Koni Omega line....
- Kaiser Fototechnik
- De Vere
- Kienzle Phototechnik
- LPL
- Bogen
- Lucky (now owned by Kenko)
- Fujifilm
- Ōmiya Shashin-yōhin K.K.
See also
- Gelatin silver process for an overview of the dominant photographic printmaking process;
- Photographic printingPhotographic printingPhotographic 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...
for an overview of analogue photographic printmaking methods; - Contact printerContact printA contact print is a photographic image produced from film; sometimes from a film negative, and sometimes from a film positive. The defining characteristic of a contact print is that the photographic result is made by exposing through the film negative or positive, onto a light sensitive material...
for a non-enlarging method of producing photographic prints; - ProjectorImage projectorAn image projector is an optical device that projects an image onto a surface, commonly a projection screen.Most projectors creates an image by shining a light through a small transparent image, but some newer types of projectors can project the image directly, by using lasers...
for a directory of projector types.