Color Differences Between Cameras
Quite often, when a new camera emerges on the market one heavily-discussed subject is if the color it records is the same, better, or worse compared to a previous model. It often happens that the color is compared based on the rendering that some RAW converter provides. Thus, an unknown variable, that being the color profiles or transforms that a RAW converter uses for these particular models, comes into play. Yet another problem with such comparisons is that they are usually made based on shots taken with different lenses, under different light, and with effectively different exposures in RAW (while the exposure settings may be the same).
Let's see how cameras compare in RAW if the set-up is kept very close to the same and the exposure is effectively equalized in RAW. It must be mentioned that light sources tend to age, so if the shots aren't taken very close in time to each other, chances are good that some of the differences between them can be attributed to the aging of the light sources.
DPReview keep a pretty good studio set-up, so let's take their studio scenes, made with 4 Canon cameras (Canon 5D Mark III, Canon 5D Mark IV, Canon 5DS, Canon 5DSr), and feed them to RawDigger (Profile Edition or Trial).
In RawDigger, we use a 4x6 grid to extract average RAW values from 24 patches of Color Checker...
...and export text files (CGATS), normalizing the exposure (data scaling) by the whitest patch (A4) and applying white balance from the most neutral patch (B4) (see three pictures below).
It's important to mention that we don't apply any forms of data manipulation here beyond black level subtraction, normalization, and white balancing. For detailed information on how to work with the grid in RawDigger please read this article.
Opening the resulting files in BabelColor PatchTool, we can compare the results (we used the 5DSr as the reference, comparing the other cameras to it). From the screenshots below, you can see that the difference is very small (because the difference is small we can use any reasonable conversion to Lab for the sake of computing deltaE -- we converted here through Adobe RGB gamma 1; alternatively, you can build matrix transforms and compare them directly), nothing a decent color profile can't handle.
It's considered that deltaE = 1 is "just noticeable difference" (often referred to as JND), and in most cases, deltaE = 2 is all we can hope for from a very accurate color transform. So, any way you look at it, the maximum difference of deltaE = 2.63, with only 4 patches having a difference exceeding the deltaE = 2 that we found between 5D Mark III and 5DSr (and taking into account the time between the shots is close to 2 years), can't seriously considered a "different color".
The light sources DPReview use for this scene are rated at 5500K, and one of the regular Canon White Balance presets in CR2 files, 5600K, is pretty close to this. Let's have a look at the white balance coefficients for this preset in FastRawViewer (white balance coefficients, outlined in red, follow RGB sequence).
The values for the white balance preset are, mostly, pretty different between the cameras we looked at. This difference may be caused by several factors, including the filter properties, microlens collection abilities, gain controls, and even changes and improvements to the responsivity to certain ranges of spectrum of the photodiodes themselves. But, as we saw, after normalization and white balancing, the difference in color is not anything to fret about.