ATN PS28 Operator's Manual page 46

ESTIMATION OF AMBIENT ILLUMINATION LEVEL
Some of usual natural light conditions and corresponding repre-
sentative illumination values are presented in Table B-1.
STANDARD NATURAL LIGHT CONDITIONS AND ILLUMINATION VALUES
STANDARD NATURAL LIGHT CONDITIONS
Quarter moon
Full moon
Late twilight sky
Twilight sky
Overcast sky in the daytime
B-1
APPENDIX B
TABLE B-1.
ILLUMINATION VALUE, LUX
0.05
0.30
1.00
10.00
500.00