With Internal Focus (IF) lenses, the focus is accomplished through the movement of internal lens elements, without affecting the overall outside length of the lens.
The lens focus group is indicated above.
There are a number of benefits to this design which is featured in most NIKKOR telephoto and selected NIKKOR zoom lenses.
-
More compact, lightweight construction.
-
A smaller and lighter set of focus elements ensure faster focusing.
-
Filters such as a polarizer or split neutral-density are not affected during focus as the filter does not rotate.
-
Petal lens hoods will remain in the correct orientation during focus.
-
In macro photography, the lens does not extend towards the subject to cause a possible lighting problem.
