The color values of Opteka Digital Grey Card set have been tested under varying light conditions and show a high degree of spectral neutrality. Using the industry-standard X-Rite spectrophotometer, LAB values of L* 63.8, a* -1.6, b* -0.4 are measured from the surface of the grey card under D50 standard illuminant. For optimum color correction, the black card achieves truly deep blacks (RGB 16,16,15). The grey card displays superior spectral neutrality with measured values of 162, 162, 160. The white card has a tested RGB value of (220, 224, 223). All three cards have excellent uniformity across a range of light sources.