DX Format vs. FX Format
Nikon DX Format is an image sensor format that is approximately 24 x 16 mm. It was created by Nikon as a feature of its digital SLR cameras, a great many of which come standard with a DX sized sensor. The dimensions of this format are about 2/3 those of the standard 35 mm format. In the past, Nikon has produced a relatively small array of lenses that conform to the DX format. Most of these lenses are consumer level zoom lenses – meaning, they are marketed as lenses that any consumer can operate as opposed to marketed towards professional photographers and their technical knowledge of lenses.
The full frame digital SLR (which is most widely known as the Nikon FX format) is a Digital Single Lens Reflex camera (or a DSLR). It is fitted with an image sensor that is the same size of a standard 35 mm camera film frame. Of course, this is in direct contest with those cameras that contain smaller sensors (the equivalent of APS-C size film, which is much smaller than the standard 35 mm frame). The use of the same image sensor size of a standard 35 mm camera helps to make the FX format a more compatible format for most cameras.
DX format uses sensors of slightly different sizes – they are all around 23 mm in width (give or take six or seven tenths of a mm) with sensor heights of about 15 (give or take five to eight tenths of a mm); however, the horizontal and vertical pixels can vary quite drastically (ranging anywhere from 2012 pixels to 4288 pixels horizontally, and 1324 pixels to 2848 pixels vertically). The 1/3 smaller diagonal size of the DX format directly yields a 1/3 narrower angle of view. This is basically the same as increasing the focal length by 50%, a 135 film camera (thusly, giving it its identifier as a 1.5 x focal length multiplier). This effect, though advantageous for telephoto and macro photography (because it is capable of producing a tighter crop without the need to increase the actual focal length, or sacrifice the depth of field), is quite a disadvantage for wide angle photography, because a wide angle lens for 135 film essentially becomes a normal lens for the DX format.
The FX allows for wide angle lenses designed for full frame 35 mm cameras to retain their same wide angle of view. Also, the pixel size is positively affected by the use of the FX format. For a given number of pixels the larger sensors allow for larger pixels or photo sites, which provide dynamic range and lower noise at higher ISO levels. However, production costs for the FX format can exceed twenty times the cost for an APS-C sensor.
Summary:
1. DX format is about 2/3 the size of standard 35 mm cameras; FX format is the exact same size as the standard 35 mm camera.
2. DX format is disadvantageous for wide angle photography; FX is quite advantageous for wide angle photography.