Luminous efficacy is used to measure how well a light source produces light. It is the ratio of the luminous flux to power. If power is replaced by the radiant flux, then it is the luminous efficacy of the radiation. Here is a table with the luminous efficacy for wavelengths in photopic and scotopic vision.
| Wavelength λ (nm) | Photopic Luminous EfficacyVλ | Photopic Conversion lm/W | Scotopic Luminous Efficacy V'λ | Scotopic Conversion lm/W |
|---|---|---|---|---|
| 380 | 0.000039 | 0.027 | 0.000589 | 1.001 |
| 390 | 0.000120 | 0.082 | 0.002209 | 3.755 |
| 390 | 0.000120 | 0.082 | 0.002209 | 3.755 |
| 400 | 0.000396 | 0.270 | 0.009290 | 15.793 |
| 410 | 0.001210 | 0.826 | 0.034840 | 59.228 |
| 420 | 0.004000 | 2.732 | 0.096600 | 164.220 |
| 430 | 0.011600 | 7.923 | 0.199800 | 339.660 |
| 440 | 0.023000 | 15.709 | 0.328100 | 557.770 |
| 450 | 0.038000 | 25.954 | 0.455000 | 773.500 |
| 460 | 0.060000 | 40.980 | 0.567000 | 963.900 |
| 470 | 0.090980 | 62.139 | 0.676000 | 1149.200 |
| 480 | 0.139020 | 94.951 | 0.793000 | 1348.100 |
| 490 | 0.208020 | 142.078 | 0.904000 | 1536.800 |
| 500 | 0.323000 | 220.609 | 0.982000 | 1669.400 |
| 507 | 0.444310 | 303.464 | 1.000000 | 1700.000 |
| 510 | 0.503000 | 343.549 | 0.997000 | 1694.900 |
| 520 | 0.710000 | 484.930 | 0.935000 | 1589.500 |
| 530 | 0.862000 | 588.746 | 0.811000 | 1378.700 |
| 540 | 0.954000 | 651.582 | 0.655000 | 1105.000 |
| 550 | 0.994950 | 679.551 | 0.481000 | 817.700 |
| 555 | 1.000000 | 683.000 | 0.402000 | 683.000 |
| 560 | 0.995000 | 679.585 | 0.328800 | 558.960 |
| 570 | 0.952000 | 650.216 | 0.207600 | 352.920 |
| 580 | 0.870000 | 594.210 | 0.121200 | 206.040 |
| 590 | 0.757000 | 517.031 | 0.065500 | 111.350 |
| 600 | 0.631000 | 430.973 | 0.033150 | 56.355 |
| 610 | 0.503000 | 343.549 | 0.015930 | 27.081 |
| 620 | 0.381000 | 260.223 | 0.007370 | 12.529 |
| 630 | 0.265000 | 180.995 | 0.003335 | 5.670 |
| 640 | 0.175000 | 119.525 | 0.001497 | 2.545 |
| 650 | 0.107000 | 73.081 | 0.000677 | 1.151 |
| 660 | 0.061000 | 41.663 | 0.000313 | 0.532 |
| 670 | 0.032000 | 21.856 | 0.000148 | 0.252 |
| 680 | 0.017000 | 11.611 | 0.000072 | 0.122 |
| 690 | 0.008210 | 5.607 | 0.000035 | 0.060 |
| 700 | 0.004102 | 2.802 | 0.000018 | 0.030 |
| 710 | 0.002091 | 1.428 | 0.000009 | 0.016 |
| 720 | 0.001047 | 0.715 | 0.000005 | 0.008 |
| 730 | 0.000520 | 0.355 | 0.000003 | 0.004 |
| 740 | 0.000249 | 0.170 | 0.000001 | 0.002 |
| 750 | 0.000120 | 0.082 | 0.000001 | 0.001 |
| 760 | 0.000060 | 0.041 | 0.000000 | 0.000 |
| 770 | 0.000030 | 0.020 | 0.000000 | 0.000 |
Eye responses are represented by luminosity function. Eye responses under bright condition is called as photopic vision and responses under lighter conditions are called as scotopic vision. The above table is based on the wavelengths of these vision.
