An enlarger is a specialised transparency
projectorused to produce photographic prints from film or glass negatives using the gelatin-silver process, or transparencies. All enlargers consist of a light source - normally an incandescent light bulb, a holder for the negative or transparency and a specialised lens for projection. The light passes through a film holder, which holds a photographic negative or transparency, having been previously exposed in a cameraand developed.
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.
Types of Enlarger
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. [http://www.ilfordphoto.com/applications/page.asp?n=113 | Ilford Photo article 'Diffuser vs Condenser Enlargers']
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. [http://www.odyssey-sales.com/products/browse.asp?range=71 | De Vere 504 DS Digital Enlarger]
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.
Horizontal enlargers are comprised of a trestle, with the head mounted on crossbars between two or more posts for extra stability. Horizontal enlarger structures are used when high quality,
large formatenlargements are required such as when photographs are taken from aircraft for mapping and taxation purposes.Fact|date=July 2008
The parts of the enlarger includes baseboard, enlarger head, elevation knob, filter holder, negative carrier, glass plate, focus knob, girder scale, timer, bellows, and housing lift. [http://www.darkroomsource.net/enlargers.shtml#what | darkroomsource.net article on enlargers | Retrieved 29/07/2008 ]
Principles of operation
The image from the negative or transparency is projected through a lens fitted with an adjustable iris
aperture, 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.
easelis 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 pinionmechanism. [http://www.photogs.com/bwworld/enlargerguide.html | Black and White World's Enlarger Guide | Accessed 29/07/2008.]
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 points; twelve printer points makes a factor of two change in exposure.
After exposure, photographic paper is developed, fixed, washed and dried using the
Automated print machines
Automated photo print machines comprise the same basic elements and integrate each of the steps outlined above in a single complex machine under operator and computer 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 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 disk 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 better quality images the negatives should be reprinted using manually operated equipment as would be found in a specialty photographic store or laboratory. Highest quality images are obtained using several preliminary test images to determine the correct exposure and filter adjustments to obtain an appropriate effect.
* The image may be printed to a size different than the negative or transparency. Without an enlarger, only a contact print 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" 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
inchprint intended for viewing in a scrapbookat 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).
Because of the change to digital, many manufacturers no longer make enlargers for the professional photographer.
Durst, who made high quality enlargers, stopped producing them in 2005, but still supports already sold models.Manufacturers old and new include:
gelatin-silver processfor an overview of the dominant photographic printmaking process;
photographic printingfor an overview of analogue photographic printmaking methods;
Contact printerfor a non-enlarging method of producing photographic prints;
Projectorfor a directory of projector types.
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Look at other dictionaries:
Enlarger — En*lar ger, n. 1. One who or that which enlarges. [1913 Webster] 2. (Photography) an optical device for making copies of photographs larger than the original, having a head for holding the original, a source of illumination to project the image,… … The Collaborative International Dictionary of English
enlarger — /en lahr jeuhr/, n. Photog. an apparatus used for making projection prints, having a head for holding, illuminating, and projecting a film negative and a bed for holding a sheet of sensitized printing paper. Also called projection printer. Cf.… … Universalium
enlarger — [[t]ɪnl ɑ(r)ʤə(r)[/t]] enlargers N COUNT An enlarger is a device which makes an image larger … English dictionary
enlarger — didintuvas statusas T sritis fizika atitikmenys: angl. enlarger; magnifier vok. Vergrößerungsapparat, m; Vergrößerungsgerät, n rus. увеличитель, m pranc. agrandisseur, m; appareil d’agrandissement, m … Fizikos terminų žodynas
enlarger — enlarge ► VERB 1) make or become bigger. 2) (enlarge on/upon) speak or write about in greater detail. DERIVATIVES enlarger noun … English terms dictionary
enlarger — noun see enlarge … New Collegiate Dictionary
enlarger — noun An optical device used to make enlarged prints from a photographic negative … Wiktionary
Enlarger — Увеличитель … Краткий толковый словарь по полиграфии
enlarger — en|lar|ger [ınˈla:dʒə US ˈla:rdʒər] n a piece of equipment used to make photographs bigger … Dictionary of contemporary English
enlarger — en largÂ·er || dÊ’É™ n. person or thing that makes larger; machine that makes prints from negatives (Photography) … English contemporary dictionary