It seems to me that my costlier (Tamron 90 f/2.8 macro) lens gives better colors than my cheap Canon 18-55 IS kit lens.
So does lens matter for color quality? What physical processes are involved in that?
Yes the lens design and construction can and does influence colour reproduction. Different glass formulas and different coatings transmit frequencies of light differently, and lens defects such as flare will likely affect the colour reproduction.
Whilst more vibrant colours are generally seen as "better" it's worth knowing that different manufacturers intentionally produce different renderings, sometimes according to cultural preferences. For example German lenses produced by Leica known for being cooler compared to Japanese designed lenses from Canon and Nikon.
So here is the mini test :)
Canon 400D camera. Both shot at f/5.6 4,0s iso 100 (just a lamp for light). Made camera white balance calibration.
So the amazing thing is that with the same exposure the 18-55 is ratehr darker.
Unfortunately the test is not quite resolutive, since there are too many variables to consider. And the test didn't cover them all.
For sure the bad exposition caused by Canon is affecting the color rendering, and this could be the effect I have experienced before.
Ok the two images above are too dark, so I take two more pics, with better exposure.
Tamron 90mm has got a clear advantage, my guess is that reasons are:
On the other hand I wouldn't really go looking at wavelength transfer function of glasses or similar physical effects.