Rear focusing system
A system where only the rear lens group moves during focusing. It eliminates changes in the physical length of the lens during focusing.
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Rear Focusing System
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Rear focus - refers to the focused area behind the picture's subject.
Rear focusing system - system where only the rear lens group moves during focusing. It eliminates changes in the physical length of the lens during focusing.
RF - Rear Focus. Lenses with this designation are equipped with a system that moves the rear lens group for highspeed silent focusing.
Both front and rear focusing Bellows that extend to permit at least a 1:1 image ratio In addition to the features listed above, the view camera has additional features that control image sharpness and distortion.
RF (rear focusing)
Only one or more rear lens groups behind the diaphragm move during focusing. Due to the small size and weight of the group it enables faster AF. There may be a change in physical length when zooming.
Some Reisekameras were not designed as tailboard field cameras for rear focusing. Instead their focusing and all possible shift and maybe tilt movements has to be done by moving and adjusting the lens board.
The rear focus system prevents the front of the lens from rotating; a circular polarizing filter can be easily attached and used. This lens is also equipped with Zoom Lock Switch that eliminates "Zoom Creep". When this lens is used with the 1.
Many Canon lenses use rear focussing (RF) or internal focussing (IF) instead. In rear focussing the lens elements closest to the camera move back and forth when you focus but the frontmost elements do not.
This lens is equipped with a rear focus system that minimizes fluctuation of aberration caused by focusing. The Super Multi-Layer Coating reduces flare and ghost, even in backlight photography.
If the focal point is behind the subject (rear focus), the distance between the two images will be wider than the optimum value (Fig. 1).
Geared controls, positive and well placed locks, spirit levels, various scales, zero detents, smooth operation, rear focussing (very important for macro work), etc.., all help. If complicated adjustments are used, a yaw-free design might help.
 See also: Focus, Lens, Focusing, Focal, Camera
  
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