User error. When I import the DNG files into my editor – Exposure 7 – I always click b&w for all images:
Which renders the histogram thus:
But occasionally I forget to do so, and get this for the same image:
My understanding is that in the B&W version I get the straight files from the camera, without any colour filter being added. In the colour version, the software guesses and interpolates. But as many longer-term members on this forum will attest, I am probably the least technical-savvy photographer here.
In short, I was in Colour mode for editing, your histogram seeing the result of that. I would send you the original DNG file for one of my images for you to examine, if your software can open DNG files. Otherwise I can send you a lower-quality out-of-the-camera jpeg.
Quote from Leica tester, Jonathan Slack: "It’s worth briefly revisiting the reason for a Monochrome camera before discussing Elliott (Typ 246) in detail: Current sensors only detect the intensity of light, not the colour. A Bayer filter is placed over the sensor with a different colour filter over each photo-site. When the image is processed (demosaicing) groups of 4 pixels are examined together and in the context of surrounding groups and the colour is calculated. The filter itself imposes a 1 to 2 stop reduction in the light reaching the sensor, and the demosaicing process reduces the resolution. With a monochrome sensor there is no need for a Bayer filter or for the demosaicing process - in theory one might expect a 4x improvement in resolution, but in practical terms it works out more like a two times improvement."
So, with the Monochrom cameras we get twice the resolution and twice the amount of light reaching the sensor. But we should not get colour from within the camera. That is my understanding.
