127 x 101.6 mm image area · 7 interactive lens diagrams
Large-format view cameras, field cameras, press cameras, and technical cameras | Nominal 127 x 101.6 mm sheet-film size with a 162.6 mm diagonal
4x5 is the workhorse large-format sheet-film size. The nominal sheet is 127 x 101.6 mm, though real holders, rebates, and film gates expose slightly less than the full sheet. Compared with roll-film formats, 4x5 gives a much larger negative and is commonly used in cameras with adjustable front and rear standards, where tilt, swing, rise, fall, and shift are part of normal operation.
For lenses, the nominal sheet diagonal is only the starting point. View-camera lenses often need image circles larger than the film diagonal so the photographer can use movements without clipping the image. Coverage angle, illumination falloff, field curvature, and distortion control matter as much as raw sharpness. In the catalog, 4x5 entries should be understood as large-format optics where the usable image circle may intentionally exceed the recorded frame.