Ilias Giarimis

Andrew wrote..
"Colour cast
I notice that noise in the shadows and blacks in general have a magenta cast if you have a warmer white balance and the magenta tint slider to the right but if you put the magenta tint slider back towards green, the warmer yellows go way too green for my liking. This could be a light issue rather than a camera one. Energy saving practical lights do give a green cast. The solution in post was to avoid anything higher than 3200k white balance – this was more keeping with the LED practical light I had for fill lighting in the scene any way."
 
 
 
 
 
Usually when developing RAW files, the magenta tint at the dark areas is due to RAW Black Point set at a lower than the correct value. Inverselly if the BP is higher than the correct we take green tint.
This behavior is because of the WB multiplicators which are almost always bigger for the R and B channels than the Green. So the result is excessive R and B components which combined gives magenta tint plus less contrast and the combination is magenta fog ...
 
Canon 5DIII's RAW Black Point (photo mode) is at 2047-2048. Same was the BP with the first gen DNGs by ML, those was not cropped and included the side "optically black" area where one can measure the Black Point value with RawDigger (and I did so ..it was 2047).
But ML tags the BP (DNG metadata) a bit lower at 2038. I believe this is an error by ML team and the BP should be 2047-2048.
There is a possibility that they chose lower BP to have the beneffit of lower noise (negative and positive deviations counteract) and better gradation at the darks ... and correct the resulting inbalance and lowish contrast with a LUT at a later stage (something that looks to me a very difficult task).
 
At the moment a user can change this tag in DNG exif (with exitool) or develop the raw with Rawtherapee and set there (in RT) the Raw.Black levels at +10.0.
 
BlackMagick went the other way .. set the BP higher (to clip what is mostly noise) .. thats why there was the problem with greenish tint developing the early DNG samples.

Andrew wrote..
"Colour cast
I notice that noise in the shadows and blacks in general have a magenta cast if you have a warmer white balance and the magenta tint slider to the right but if you put the magenta tint slider back towards green, the warmer yellows go way too green for my liking. This could be a light issue rather than a camera one. Energy saving practical lights do give a green cast. The solution in post was to avoid anything higher than 3200k white balance – this was more keeping with the LED practical light I had for fill lighting in the scene any way."
 
 
 
 
 
Usually when developing RAW files, the magenta tint at the dark areas is due to RAW Black Point set at a lower than the correct value. Inverselly if the BP is higher than the correct we take green tint.
This behavior is because of the WB multiplicators which are almost always bigger for the R and B channels than the Green. So the result is excessive R and B components which combined gives magenta tint plus less contrast and the combination is magenta fog ...
 
Canon 5DIII's RAW Black Point (photo mode) is at 2047-2048. Same was the BP with the first gen DNGs by ML, those was not cropped and included the side "optically black" area where one can measure the Black Point value with RawDigger (and I did so ..it was 2047).
But ML tags the BP (DNG metadata) a bit lower at 2038. I believe this is an error by ML team and the BP should be 2047-2048.
There is a possibility that they chose lower BP to have the beneffit of lower noise (negative and positive deviations counteract) and better gradation at the darks ... and correct the resulting inbalance and lowish contrast with a LUT at a later stage (something that looks to me a very difficult task).
 
At the moment a user can change this tag in DNG exif (with exitool) or develop the raw with Rawtherapee and set there (in RT) the Raw.Black levels at +10.0.
 
BlackMagick went the other way .. set the BP higher (to clip what is mostly noise) .. thats why there was the problem with greenish tint developing the early DNG samples.