In digital cameras, the camera's
format refers to the size of its image sensor. Nikon makes a DX-format sensor
and an FX-format sensor. The DX-format is the smaller sensor at 24x16mm; the
larger FX-format sensor measures 36x24mm which is approximately the same size
as 35mm film.
Different NIKKOR lenses are designed
to accommodate the different camera sensor sizes. In the case of DX cameras
with their smaller sensors, corresponding DX lenses have been designed. The DX
designation can be found in the lens name, i.e. AF-S DX Zoom-NIKKOR 12-24mm
f/4G IF-ED. These lenses are smaller and lighter in weight and address the
market's need for affordable, high-performance lenses with a variety of focal
lengths and zoom options.
The DX sensor makes possible the
production of lighter, smaller cameras, but because it covers a smaller portion
of the image projected by the lens, a 1.5x crop factor (so called because the
smaller sensor crops the image compared to an image from a 35mm film frame) is
introduced. This means, for example, a 24mm lens on a DX sensor camera will
provide an approximate 36mm view.
The FX sensor, with more "light
gathering" area, offers higher sensitivity and, generally, lower noise.
There is, of course, no crop factor present with the FX sensor.
DX cameras have the added benefit of
being able to use both DX and non-DX NIKKOR lenses—those lenses without the DX
designation in their names, i.e. AF-S NIKKOR 14-24mm f/2.8G ED. And here's why.
Each lens is designed to cast an
image circle on the camera's sensor. The circle cast by a DX lens is smaller
and corresponds to the size of a DX sensor. Non-DX lenses cast a larger image
circle corresponding to an FX-format sensor. The DX-format camera can use both
types of lenses (DX and FX) since the non-DX lens image circle is larger than
needed on a DX-format camera.
Diane
Berkenfeld
On an FX-format camera with a DX lens mounted, the camera will
automatically engage its built-in DX crop mode, thus recording an
image only from the center section of the sensor.
Tidak ada komentar:
Posting Komentar