Nikon extension rings can be used singly or in combination to vary the reproduction
ratio of lenses from 20 to 300mm. They are mounted between the camera body and
the lens, As a rule, the effect becomes stronger the shorter the focal length
of the lens in use, and the longer the focal length of the extension ring. Through
the-lens exposure control automatically compensates for lens extension. Manual
and aperture-priority auto-exposure control modes are possible. Manual focus only.