We report results of an experiment measuring contrast sensitivity as a function of spatial frequency, location in colour space and direction of variation. Stimuli comprised sinusoidal gratings on one side and a uniform field of the same mean colour on the other. The experiment used forced choice to measure thresholds for many observers and numerous spatial frequency-mean colour-direction of variation combinations. Earlier data covered the spatial frequency range from 0.44 to 20 cycles per degree (cpd) and suffered from quantization effects at peak sensitivities. That data showed no meaningful dependence on any other independent variables, such as C*, as would have been expected from common colour difference metrics. The current experiment corrects the quantization effects, seeks more explicitly chroma or hue dependence and extends the low spatial frequency range to 0.19 cpd. We have found only a weak dependence on hue (in addition to the dependence on spatial frequency).