Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
(A) Noise in the AF ring (arrow), manually filled with black (gray value = 0). (B) Inappropriate AF ring that has a spiky part projecting out in the direction of 10 o'clock. (C) Inappropriate AF ring that has a notch in the direction of 2 o'clock.
