The front nodal point is where rays of light entering the lens appear to aim. The rear nodal point is where the rays of light appear to have come from, after passing through the lens. Nodal points are used to calculate optical measurements.
-Equivalent focal length - distance in a lens between the front nodal point and the focal plane when the lens is set to focus a subject at infinity. In a telephoto lens the equivalent focal length is shorter than the back focus.
To render closer objects in sharp focus, the lens must be adjusted to increase the distance between the rear nodal point and the film, to put the film at the image plane. The focal length f, the distance from the front nodal point to the object to ...
 See also: Nodal point, Focus, Plane, Focal, Short
  
|
RSS
