- I know some people shoot manual mode and do not like to shoot auto or semi auto because they believe they can control everything, but all they do is shoot in manual mode, dial the aperture and then change the shutter speed until display meter is point to 0 (-|---0---|-)
This could not be
further from the truth.
just out of curiosity, how do you know that it's not true? I know a few photographer friends who do exactly that the vast majority of the time. Or they want to make an adjustment to the exposure of lets say 1/2 stop, so they use manual mode. But as I've pointed out to them it can just as easily be done in aperture preferred mode using EC.
Ok.
The zero does not indicate "proper exposure" it indicates "0ev from reference". What this means is that there is as much light at the meter as there was when the meter was calibrated in the first place, which is 12.5% or 18% reflected light, depending on the meter. You may already know this, but few photographers really realize what that means is pretty unsubstantial.
Zeroing a meter will render whatever is being metered or chosen by the fancy-pants, multi segment is going to be rendered in a similar way to it's calibrated reference. But this says absolutely nothing about the scene itself, and more important how you want the scene to be rendered - and what if there is no middle grey to choose from? The result will be a missed exposure.
Modern in-camera meters do a pretty good job of compensating for the latter, but they do so in accordance of their programming, which is great, especially in situations where you don't have the luxury of diddling around with a spot meter - after all, these systems were developed for the press photographers of the late 20th century who needed fast, objectively accurate and most important predictable results in less than ideal circumstances.
But in other situations where control is more valued that speed these metering systems are often far from idea. What if you want a near silhouette with ample but subtle shadow detail against a turbulent, yet brightly lit sky? You could use AE and compensate - but by how much would you compensate?
To do this, you could spot meter off the tree. If you dialed in "zero" it would render too bright, and it is likely that the sky would blow out. You could meter off the sky and zero it in, and while the sky might have enough detail, the tree would have no detail at all.
Instead, of just "zeroing" the meter to whatever arbitrary condition it was calibrated, you can use "zero" as a predictable reference. We know that whatever the meter says, by stopping down two or three stops the tree will render how we expect it to. So, to do this, you can meter off the tree, and decrease exposure by two stops - placing it in Zone III. Provided that the highlights aren't blown, you done.
There are better ways to handle this, ofcourse, but every method requires exposure compensation one way or another. And yes. You can certainly do this in AE as well using the EC parameter. However, manual mode works well because you are not fixed to just shutter or aperture adjustment. In manual mode I can consider what the drawbacks and advantages of every change I make in relation to the subject: will increased noise be better than shallow DOF; will increased DOF be better than a shorter exposure; is this photograph even possible in the current circumstances.
But using AE makes it very hard to visualize what each parameter is doing and how they are related. And this is really essential to having complete control over your camera - no matter what metering mode or exposure method is used.
