duplicate negative. The contact exposure process usually refers to a film negative used in conjunction with printing paper, but the process may be used with any transparent or translucent original image printed by contact onto a light sensitive material. Negatives or positives on film or even paper may for various purposes be used to make contact exposures onto different films and papers. Intermediary products such as internegatives, interpositives, enlarged negatives, and contrast controlling masks are often made using contact exposures. Computer screens and other electronic display devices provide an alternative approach to contact printing. A permanent image (negative, positive film or transparency, or translucent original) is not used, instead the light sensitive material is exposed directly to the display device in a dark room for a controllable duration. The resulting image generated by this mixed digital/analogue technique has been coined "laptopogram". While limited by the image display device resolution, which can be much inferior to film negatives, the widespread use of electronic displays provides great potential to this unorthodox contact printing method. In contact sheet photography, the traditional contact sheet is used as a way to make pictures consisting of partial photos. The resulting image spans the whole sheet, divided into squares by the black borders of the film. Artistic and practical considerations Photographers praise the beautiful intermediate gray or color gradation that results from making prints this way. Each print is necessarily the same size as the corresponding image on the negative. This makes contact prints from large-format negatives, especially 5×7 inch and larger, most usable for fine-art work. Smaller contact prints, from films and formats such as 135 film cassettes, 35 mm (24×36 mm images), and 120/220 roll film (6 cm), are useful for evaluation of exposure, composition, and subject. It is cheaper and easier to avoid making conventional prints of all the exposures with an enlarger; the photographer prints only the best negatives. Selection is usually made using a loupe — a special magnifying glass with a transparent base — to examine the tiny prints, still aligned as they are on the negative strips. Negatives themselves can be examined with a loupe, but blacks and whites are the reverse of what is seen through the view finder (hence: a negative), which makes it more difficult to interpret the images. Contact sheets can easily be stored in files in the dark, along with the negatives. Notable photographers Edward