A system introduced by Nikon for some of its lenses where the lens aperture diaphragm in the lens is controlled electromagnetically rather than by the traditional mechanical linking. This gives more accurate and consistent exposures, especially during continuous shooting, where the lens diaphragm may be adjusted many times a second.
The maximum light-gathering power of a lens and a major selling point.It lets you use faster shutter speeds or lower ISO settings in poor light.This lens has a maximum aperture of 1:2.8. This is the same as f/2.8 – different makers use slightly different terminology.
Mechanism inside a lens which uses interlocking metal leaves, or ‘blades’, to produce a variable-sized aperture within the lens. This is used to control the amount of light passing through and hence the exposure.
Usually you view the scene with the camera lens wide open and it only stops down to your chosen aperture the moment you press the shutter button, so it’s hard to judge just how much depth of field the final photo will have. The depth of field preview stops the lens down to the taking aperture, though, so you can judge the effect in the viewfinder or on the LCD display.
Depth of field is the near-to-far sharpness in a picture. If both foreground and distant objects are sharp, there’s lot’s of depth of field. If only the subject is sharp and the foreground and background are blurred, it’s shallow depth of field. Both are fine, depending on the effect you’re trying to achieve in your picture. Depth of field is affected by the lens focal length (longer focal lengths produce shallower depth of field), the lens aperture (wider apertures produce shallower depth of field) and focus distance – the closer your subject the shallower the depth of field. Shallow depth of field can product attractive background blur in portrait shots, for example. This is often referred to as ‘bokeh’, though bokeh is actually something slightly different.