I’ve used Raw Therapee for many years with Canon cameras, most recently a 1D X. All of them have had a low-pass filter in front of the sensor to avoid aliasing or moire’ patterns. I’ve recently started using a 5Ds R, which doesn’t have this filter. It gives sharper images but an increased risk of these artefacts. Edit: apparently it has the filter and then another filter to cancel it! But the effect is the same.
The raw files load correctly in Raw Therapee (5.8) and look good. However, the profile I used for the other Canon bodies doesn’t give the best results. Firstly, there is less need for sharpening. I normally use R-L deconvolution with a radius of 0.75. That’s only moderate sharpening for the 1D X, but with the 5Ds R it over-sharpens, giving a white border around tree branches for example, when these branches are against a light-coloured wall. Reducing the radius to 0.5 fixes that, although the sharpening is then having little effect. This is fine; one of the main reasons for sharpening is to undo the blur caused by the low-pass filter which the 5Ds R doesn’t have.
I also noticed some red-green fringing around the edges of the branches. This appears to be introduced by demosaicing. I found that changing the method to LMMSE mostly resolves the problem. The help text says it’s intended for high-ISO images, but with the 5Ds R it also helps with those at ISO 100.
I do have Defringe turned on, removing cyan and magenta fringes, but I believe this is intended more for fringing caused by the lens rather than pixel-level sensor artefacts.
Anyway, I’m surely not the first person to use Raw Therapee with the 5Ds R. What experience have others had? Are there some canned profiles which are tweaked to give a good result with this body?
