Nikon Camera F3AF - Manual (Page 38)

Dark subject (lllust. 1 )
The red X blinks to show insufficient scene brightness. In this
case, focus manually, or perform autofocus/focus-aid operation
on an alternate subject at the same distance which is lighter
in tone.
Low-contrast subject (lllust. 2), small or finely
detailed subject (lllust. 3)
The red X lights up continuously. In this case, focus manually, or
perform autofocus or focus-aid operation on an alternate sub­
ject at the same distance which has more contrast or is larger.
Subject with no vertical lines (lllust. 4)
The red X glows continuously. In this case, turn the camera ver­
tically and perform autofocus or focus-aid operation, or focus
manually; alternatively, perform autofocus or focus-aid oper­
ation using an alternate subject at the same distance which has
vertical lines.
Subject with high reflectivity (lllust. 5), backlit
subject (lllust. 6), or scene with both far and near
subjects (lllust. 7)
In these cases, both red arrows or the red X light up contin­
uously. If the red X appears, focus manually. If both red arrows
are lit, use the matte portion of the screen to check focus. If
your desired subject is out of focus, then focus manually. If it is
in focus, take the shot.