The raw histogram should be telling you why, looking at the raw histogram it shows that for that raw file you are underexposing by 1 stop half the amount of light your camera can store, while your cameras histogram does not shot this and that your red and blue channel captured the same amount of light when they did not
Oh dear, you really have no idea and you claim to be a professional photographer.
The raw histogram shows how close the actual raw data is to clipping or otherwise.
The camera histogram is a histogram of image data that has been processed from the raw data and so can be only an approximation of the raw data histogram.
If that is the case then your white background is a stop below the clipping, and you could easily add a stop to the exposure does your cameras histogram tell you this?
Forget the RGB histogram unless you’re shooting only jpegs or using uniWB for raws (Google it, if you’re unfamiliar). The luminance histogram can be useful enough with some cameras the (highlight end of it anyway), but it it can easily fail to register small (but important) areas of potential overexposure. I don’t use histograms at all with my cameras (Fuji) as the highlight warning blinkies are very reliable for determining highlight exposure in pretty much any situation and operate much like a full-screen spot meter for highlights - which shows you precisely where any potential highlight detail is in danger of clipping. Far more useful than a histogram, IMO. YMMV. A bit of experimentation using RawDigger is generally in order to dial in a reliable methodology with your gear.
Instead of making yourself look more foolish with every post, just cut your losses, put your hand up and just admit you learnt something new this thread about raw data and their histograms and move on.
you are right and i noticed as well ,Raw Digger missed some near clipping highlights and when converted to Tiff there was no detail at all in them. pretty useless if you ask me, yet everyone raves about it unless ive missed something .
That's a stupid thing to wait for because no-one is saying the in camera histogram is useless.
If shooting sooc jpegs the in camera histogram is fine.
If shooting raw the in canera histogram is an approximation of the raw data histogram. How seriously you take it is up to the photographer and their needs and goals.
The funny thing is that rawdigger did not miss the near clipping highlights because there was none close to clipping in the raw file, and that it was your raw conversion that caused the clipping