histogram exposure mode?

I've mentioned this in threads before, but about 5 of us were shooting (landscapes) Sunday morning and I mentioned it then when someone was grumbling about exposure issues...

Why hasn't a camera manufacturer come up with a "meter" mode where it keeps BOTH ends of the histogram from clipping? Dial in some -EV and you get the shadows clipped a bit (or more), dial in some +EV and you get the highlights clipped a bit (or more).

It wouldn't be idea for everything, or maybe not even a lot of things, but for what/how I shoot, I could use it for at least 80% of what I shoot. Anyone else?

The width of the histogram is a function of the brightness range of the scene. Fill the frame with a grey card and you would have to grossly bungle the exposure in order to send the histograph to one end or the other. Shoot a black cat wearing a medium grey hat and sitting in sunlit snow and no current camera can expose the scene without clipping. Extreme examples? Sure, but the point is that if the tonal range exceeds the DR of the camera, a decision will have to be made about what gets chopped. Human beings are better (or at least should be) at decision making than cameras.

The problem lies with the scene not the metering.. If your histogram is clipping both ends it means the dynamic range exceeds the cameras ability to record such a wide dynamic range..

Just thinking here....but if the DR of a scene is narrow enough to be entirely recorded by the sensor, wouldn't the current metering system set to evaluative with no EC do just as you describe for the most part?

I get what you're going for with this idea. It's certainly something I could use with a lot of what I shoot since the dynamic range doesn't push the camera's capabilities all the time. In that case it shouldn't be a terribly difficult bit of programming to tell the camera to increase exposure to push the histogram up, effectively automating the "expose to the right" concept. If, like yogestee says, the dynamic range is greater than what the camera can record then it wouldn't be of any use.

In essence it could be implemented in an automated exposure mode where it would automatically boost the exposure but prevents the highlights from clipping (at least beyond a certain % of pixels or some sort of histogram based statistics) should the dynamic range be less than the camera's recording ability. To be able to determine this it would have to calculate exposure based off a live sensor readout since the exposure metering sensor wouldn't provide enough information I think, but with Live View that certainly is a lot easier now. Pushing the exposure up seems like the only useful way to respond to a narrow dynamic-range scene, since reducing it to move the histogram to the left would just result in more noise.

The 1DM3 (and, I presume, the 1Ds3) has a Multi Spot Metering Mode which is interesting if you are concerned about keeping certain things within the exposure range. You select up to 8 points covering your critical range of highlights and shadows, and the meter sets an average exposure factoring them in.

I've only briefly tried it, so don't know how good it is -- when I did test it out it came up with something very close to the Manual exposure I set for the scene. It would be interesting, for example, to see how it treated a scene with snow and deep shadows.

My EOS 3 had a multi-spot metering mode which I never used. I think I was scared to waste film experimenting with it until I was comfortable with how it worked. I've never tried it with my 1D MK II oddly.