Appendix 1: Measuring Light Levels with a Camera
Equipment Required
- 35 millimetre camera with a built-in light meter; and
- white cardboard (about 30 - 40 square centimetres).
Method
- place the cardboard in the same position and at the same angle as the object or area that is being measured;
- set the camera to 800 ASA and without casting a shadow on the white cardboard, take an f-stop and shutter speed reading with the camera;
- the cardboard should fill the frame in the viewfinder of the camera; and
- use the coordinates obtained to determine the light level using the table shown below (for example, f8 at 1/30 sec = 700 lux).
Lux | 88 | 175 | 350 | 700 | 1400 | 2800 | 5500 | |
F-stop | 2.8 | 1/30 | 1/60 | 1/125 | 1/250 | 1/500 | 1/1000 | 1/2000 |
4 | 1/15 | 1/30 | 1/60 | 1/125 | 1/250 | 1/500 | 1/1000 | |
5.6 | 1/8 | 1/15 | 1/30 | 1/60 | 1/125 | 1/250 | 1/500 | |
8 | 1/4 | 1/8 | 1/15 | 1/30 | 1/60 | 1/125 | 1/250 | |
11 | 1/2 | 1/4 | 1/8 | 1/15 | 1/30 | 1/60 | 1/125 | |
16 | 1 | 1/2 | 1/4 | 1/8 | 1/15 | 1/30 | 1/60 | |
22 | 2 | 1 | 1/2 | 1/4 | 1/8 | 1/15 | 1/30 | |
32 | 4 | 2 | 1 | 1/2 | 1/4 | 1/8 | 1/15 | |
Shutter speed in seconds |
The values quoted in the table were obtained using a Gossen Lunasix 3 light meter, cross referenced with a range of Nikon cameras. Regard the readings as approximations only.