Nikon DX format

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The Nikon DX format in an image sensor format with an image area of 23.7x15.7mm.

The format was created by Nikon for its digital SLR cameras, all of which are equipped with DX sized sensors. The DX format is slightly larger than the 22x15mm area of the APS-C format, and about 1.5× smaller than the area of 135 film. This means with a DX format sensor, the effective angle of view is reduced by 1.5 from the angle of view of the 135 film with the equivalent lens. This is advantageous for telephoto and macro photography as it effectively multiplies the focal length of the lens by 1.5 thus producing bigger image at the same focal length compared to 135 film while maintaining the same depth of field, aperture and focal distance. However it becomes disadvantageous for wide angle photography as a wide angle lens for 135 film (eg. 28mm) effectively becomes a normal lens for the DX format (28×1.5=42mm 35mm equiv.). This led to the growing development of the DX format lenses for the Nikon F-mount, with smaller image circle which reduces the size and weight of the lens and also enables the manufacture of special wide angle lenses for the DX format sensor (eg. 12mm focal length) that would otherwise be very hard to make with an image circle of 135 film. If DX format lenses are used on 135 film cameras vignetting will occur as the image circle doesn't cover the whole area of the 135 film.