Today’s Question: I’m confused. If I’m shooting in manual mode but I enable auto ISO on the camera, am I really still in manual mode? Isn’t it not really manual because the camera is changing the ISO setting?
Tim’s Quick Answer: If you set your camera to manual exposure mode but with auto ISO enabled, I would say you are using a semi-automatic exposure mode (similar to aperture priority) rather than a true manual exposure mode.
More Detail: In my view there are three categories of exposure modes on cameras. Manual mode means you are controlling all exposure settings. Semi-automatic means you are selecting one or more exposure settings and allowing the camera to select other settings. Fully automatic means you are leaving all decisions about exposure settings up to the camera.
Based on this way of thinking, if you enable auto ISO when using the manual exposure mode, you aren’t using a true manual exposure mode.
If you use aperture priority mode, you select the lens aperture setting and the ISO setting (with auto ISO disabled) and you let the camera choose the shutter speed. If you’re in shutter priority mode you’re selecting the shutter speed and the ISO setting and allowing the camera to select the lens aperture. In both cases you can use exposure compensation to refine the overall exposure result.
Manual exposure mode with auto ISO enabled is exactly the same as the aperture priority and shutter priority modes, except for which value you’re letting the camera choose. You dial in the lens aperture and the shutter speed, and the camera chooses the ISO setting.
Having said all that, in my view this is really an issue of semantics. As far as I’m concerned, all that really matters in terms of the exposure for a photograph is what settings were used for lens aperture, shutter speed, and ISO setting. The only real question is how you’re going to get to those settings. Regardless of whether you’re using an automatic, semi-automatic, or fully manual exposure mode, what really matters is what final settings you arrive at.
In other words, as far as I’m concerned there’s no shame in using an automatic or semi-automatic exposure mode, and there should be no great pride in using manual mode. What really matters is what the final exposure settings are. Whatever process you find most helpful for getting to the right exposure settings is perfectly fine as far as I’m concerned.
