"full frame" with respect to fisheyes has nothing to do with the use of the term to designate a digital sensor measuring 36x24 mm). The angle of view produced by diagonal fisheyes only measures 180° from corner to corner: they have a 180° diagonal angle of view (AOV), while the horizontal and vertical angles of view will be smaller. For an equisolid angle 15 mm full-frame fisheye, the horizontal AOV will be 147°, and the vertical AOV will be 94°. One of the first diagonal fisheye lenses to be mass-produced was the Nikon Fisheye-Nikkor F 16mm 3.5, made in the early 1970s. To obtain the same effect on digital cameras with smaller sensors, shorter focal lengths are required. Nikon makes a 10.5 mm fisheye for their APS DX SLRs. Several other companies make "full frame", i.e. diagonal, fisheyes for APS and m43 cameras, see next paragraph. Portrait or cropped-circle fisheyes An intermediate between a diagonal and a circular fisheye consists of a circular image optimised for the width of the film format rather than the height. As a result, on any non-square film format, the circular image will be cropped at the top and bottom, but still show black edges on the left and right. This format is called a "portrait" fisheye; historically, it has been rather rare - only the 12 mm f/8 Accura lens (see list below) directly follows the portrait principle. Today however, a portrait fisheye effect is easily achieved by using a fisheye lens intended for full coverage of a smaller sensor format, like an APS diagonal fisheye on a 35 mm full frame camera, or an m43 diagonal fisheye on APS. Miniature fisheye lenses Miniature digital cameras, especially when used as security cameras, often tend to have fisheye lenses to maximize coverage. Miniature fisheye lenses are designed for small-format CCD/CMOS imagers commonly used in consumer and security cameras. Popular image sensor format sizes used include ", ", and ". Depending on the active area of the image sensor, the same lens can form a circular image on a larger image sensor (e.g. "), and a full frame on a smaller one (e.g. "). Examples and specific models For a comprehensive list of all current and all past fisheye lenses, see External Links below. Noteworthy fisheye lenses for APS-C cameras The APS-C image sensor used in Canon cameras is , or on the diagonal, which is