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Conversion - PPF to Foot-candles

 

PPF (μmol m-2 s-1) to Foot-candles

Foot-candles to PPF (μmol m-2 s-1)
Sunlight 5.01 Sunlight 0.200
Cool White Fluourescent Lamps 6.87 Cool White Fluourescent Lamps 0.146
High Pressure Sodium Lamps 7.62 High Pressure Sodium Lamps 0.131
High Pressure Metal Halide Lamps 6.60 High Pressure Metal Halide Lamps 0.152
Low Pressure Sodium Lamps 9.85 Low Pressure Sodium Lamps 0.102
Multiply the PPF by the conversion factor to get foot-candles. For example, full sunlight is 2000 μmol m-2 s-1 or 10,020 foot-candles (2000 ∗ 5.01). Multiply the foot-candles by the conversion factor to get PPF. For example, full sunlight is 10,020 foot-candles or 2000 μmol m-2 s-1 (10,020 ∗ 0.2).

PPF to Foot-candle Reference Table

Sunlight

Cool White Fluorescent

If PPF is:

then, fc is:

If PPF is:

then, fc is:
10 50.1 10 68.7
100 501 100 687
200 1,002 200 1,374
300 1,503 300 2,061
600 3,006 600 4,122
1,000 5,010 1,000 6,870
∗ 2,000 ∗ 10,020 2,000 13,740
∗  Full sunlight at solar noon or on a clear summer day.

Definitions

Photometric Units, Illuminance

Foot-candle:

one lumen per square foot.  The 16th General Conference on Weights an Measures (CGPM), Oct. 1979, decided that the candela is the luminous intensity of a source emitting monochromatic radiation of frequency 540 x 1012 Hz and radiant intensity 1/683 watt per steradian.  This corresponds to 683 lumens per watt of radiation at approximately 555 nm wavelength, which is near the maximum of the standard photopic spectral luminous efficiency curve.

LUX:

one lumen per square meter; differs from foot-candle by about a factor of 10.

Quantum Units, Photon Flux Density

Microeinstein:

per second and square meter (μE m-2 s-1).  The einstein has been used to represent the quantity of radiant energy in Avogadro's number of photons and also Avogadro's number of photons.  The second definition has the einstein equal a mole of photons. While commonly used as a unit for photosynthetically active radiation (PAR), the einstein is not an SI unit.

Micromole:

per second and square meter (μmol m-2 s-1).  This term is based on the number of photons in a certain waveband incident per unit time (s) on a unit area (m2) divided by the Avogadro constant (6.022 x 1023 mol-1).  It is used commonly to describe PAR in the 400-700 nm waveband.

Definitions Source

Thimijan, Richard W., and Royal D. Heins. 1982. Photometric, Radiometric, and Quantum Light Units of Measure:  A Review of Procedures for Interconversion. HortScience 18:818-822.