n.an enlarged representation of an image on microformChisholm 1963, 525The traditional silver halide type of photographic paper has long been the standard medium for preparing microfilm enlargements, or “blowbacks.”Poole 1965, 584By using the 15:1 reduction ratio instead of 30:1 a full-size blowback of the original could be produced on an 18″ X 24″ reader-printer.Nelson 1968, 406The unit will project a full size blowback from a standard size microfiche at a distance of 4 ft.Reitz 2004, 83blowback: A hard copy enlargement of an image on microform. Most libraries provide reader-printer machines for enlarging and making copies of documents available on microfilm and microfiche.GPO 2017, 1The document pertains to all microform types procured by the U.S. Government Publishing Office. The end use of these microforms is to be any or all of the following: ¶ Producing additional microforms; producing hard copy blowback (paper prints); and viewing on micrographic viewing equipment, including automated retrieval systems.the process of magnifying an image on microformLathrop 1980, 336Large-format material can be microphotographed on 35 mm. roll film, but 70 mm. or even 105 mm. film is preferred because of lower reduction ratios, superior resolution, and definition which facilitates enlargement (“blowback”), and because one large drawing can be fitted in its entirety onto a single frame.ALCTS 2013Microfilm readers should be able to accommodate both 16mm and 35mm rolls of film. The magnification capability should be between 18x and 24x. Ideally, to achieve full blowback, the screen size should be as large as the original document.
