Light Sketch Series 2

Light sketch Series 3

Illuminance Measurement

1. Measure the horizontal illuminance (fc) at your workstation using the GE pocket light meter. Take several measurements over the work area.

1.4 31.3 Footcandles

Convert the readings to footcandles: (1 footcandle = 10.76 lux or 10 lux for convenience)

14 313 Lux

2. Would you have a good idea of the overall illumination in this room if you were to average everyone's readings?

Estimating the Reflectance of a Surface

3. Measure the reflectance of a piece of paper. Again using the pocket light meter, measure the light falling onto a 8.5 x 11 inch piece of plain white paper. Reverse the position of the meter so that the cell points toward the surface of the paper, move the cell (white area) of the meter away from the surface 1-2 inches and take a second reading.

Reflectance = Reflected Light/Incident Light

Reflectance = .8 / 2.0 = 4

Reflectance % = 40%

Estimating the Transmittance of a Material

4. Measure the transmittance of a piece of paper. Take a light meter reading on your work area. Leaving the meter in place, next, place the material to be tested on the light meter cell, then take a second reading.

Transmittance = Reading With Paper/Reading Without Paper

Transmittance = 7.8 / 40 = .195

Transmittance % = 19.5%

Use the lightmeters now to measure illuminance levels on horizontal and vertical surfaces in any one space in the Gatewood Studio Arts Building with your group. Find the reflectances of all surfaces. Draw isolux diagrams. Note the time and date on your sketch. Include in your sketchbook and blog by September 29.