It probably hasn't occurred to many photographers that they can automate exposure while in "manual" mode. Although this sounds like an oxymoron, it's really not.
What if you would like a specific aperture to control either resolution or depth of field. But you'd also like to control the shutter speed to work well with lens vibration control or perhaps freeze action. But you don't want to give up automatic exposure.
You can have it all simply by switching to "Auto ISO". Now, with the camera set to manual, you can control the aperture and shutter, while the camera adjusts the ISO to suit the required exposure.
There's a variation on this theme, when you use a flash while in manual mode. That topic is discussed in an earlier article I wrote here:
For skeptics, there's a way to prove that you still get the correct exposure using the technique described above. It's called a histogram. Simply chimp the shot and verify that your histogram looks correct.
Sample camera Auto ISO menu option
Along with this extra power comes extra responsibility, of course. If you truly want “manual” exposure, then remember to turn Auto ISO OFF…