50D Histrogram

[u8myufo]

I was wondering if anybody could enlighten me about the histrogram? If I use a preset WB or manual one, for some reason the blue channel is always hanging back to the left whereas the Red and Green seem to be spread nicely across the middle of the graph. So being a one for messing I had a play with the white balance shift menue in camera, and moved the Blue channel across and down slightly which has brought the Blue channel more inline with the rest and imo has improved the picture. Just wondering if anybody has touched upon this at all and what was the outcome? Is there a logical reason why the Blue is over to the left more than the other channels? Does this happen just with the 50D or will it always be the case whichever make and model of digital camera? Something tells me it will be a long drawn out technical answer
Thanks for any info.

 

[Canon Bob]

Long, drawn out technical answer at this time in the morning....forget it.

Will a few facts with more than a little supposition thrown in do you?

The luminosity histogram is made up by summing the RGB channels but NOT in equal proportions. Green accounts for around 60% of the result, red 25-30% and the remainder is the blue channel.

So what are the pros and cons of blue?
Pros.....very good for sky
Cons....dodgy for flesh tone and makes things look cold (and we all prefer warm, don't we )

Lets jump forwards to blinkies (blown highlights to you ). Safe to say that they're most often seen in shots with some sky up the top (a fair bit of blue).
Noise is the next problem.....shadows and dark areas (under exposed red channel stuff).
Back to the blinkies....they are show when TWO channels are clipped (not just one) and the normal remedy is to reduce the exposure a tad. This reduction will likely push back the red channel to and our noise becomes a little more of a problem.

Sussed it?
A retarded blue channel makes women's skin look softer and helps prevent us inadvertently have noisy shadows.

Worthy mentioning that the histogram you see is derived from the embedded JPG and may be a quite inaccurate representation of what the RAW file contains (compare the camera's LCD histogram with ACR or CS2,3,4,5's offering for the same shot)

Should you require any more potential BS from Bob, please don't hesitate to ask

Bob