Spectrum-locus convexity confers to human vision the property that optimal colors are 1-0 with at most two transition wavelengths. It also confers illuminant-invariance of the CW/CCW chromaticity ordering of certain reflectance triads. The same holds for cameras, and provides a less stringent criterion for camera quality than that of Maxwell and Ives. Unlike in applications that design reflectance spectra, the camera convexity criterion has the goal of ensuring that cameras and humans share the same non-reversing reflectance triads, not of ensuring illuminant-invariance of the triads themselves. Convexity may be a useful metric, but is undefined when the sensors are non-overlapping. This paper will qualitatively explore these issues.