Pentax R-315(N) - Manual (Page 28)

3-7 Target Sighting
[Auto focus]
The Auto focus mechanism is very precise but will not function under every
condition. There is a slight possibility of focusing failure owing to brightness,
contrast, the shape and size of the target.
In such a case, press the AF button and focus on the target by operating the
Power focus key or the AF ring.
<Target examples which are hard to focus>
No contrast like a white wall Bright back light
Obstacle in front of a target A wall composed of
single horizontal lines
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3 PREPARATION FOR SURVEYING
PENTAX R-300 (p20-52) 10/30/02 11:08 AM Page 26