WHY, HOW, & WHEN YOU NEED TO OVERRIDE
YOUR BUILT-IN EXPOSURE LIGHT METER

I am going to explain this in non-technical terms. Let's start with the problem, before I get into the solution. All cameras have a built-in exposure light meter, which measures reflected light, not the light falling on a subject--that's the problem. Why is it a problem? Let's think in terms of black and white for a moment. If we photograph a black or very dark subject, the meter will lighten it up to get it back to gray. If we photograph a white or very bright subject, the meter will darken it to get it back to gray. It will always try to bring the lighting, the exposure, to middle gray. Why? It was designed to give us the "correct" exposure, i.e., gray. 

In color photography, "gray" would be mid-tones, between black or very dark and white or very bright. Instead of getting a white snowman, the meter, trying to give me the "correct" exposure, will give me a gray snowman.

Below is an in-the-field example of this problem. I was at White Sands, New Mexico recently. Before I go on, click on the link and notice how gray the white sand looks. Now, back to my story. When I was at White Sands, I made sure to take a couple of instructional photos for my classes and workshops. Before and After, if you will. Below is a photo of gray white sand. That is what the built-in exposure light meter gave me, which I knew it would. This is a field, real life, example of the problem.   

Okay, so now we know about, understand, and see the problem. Before I share the in-camera solution, let me set the stage. I shoot on AV exposure mode, that is, aperture priority. Obviously, if someone shoots on manual exposure, the adjustments or solutions would also be done manually. Now, back to shooting on aperture priority. I am in total control of my desired depth-of-field, or f/stops, which is my style. In the above example, once I set the f/stop I needed to get the depth-of-field I wanted, the built-in exposure light meter gave me the corresponding shutter speed it thought I needed in order to give me the "correct" exposure. You've already seen the results of that.

The solution. Every camera has an exposure compensation dial on the camera body. It is a very tiny round or square button with a +/- in it. It is either on top of the camera or on the back of the camera. Rather than spend too many words explaining how it works, I'll let this gentleman explain it for you on this Youtube video. You might need to go to the index of your camera manual to find where it is.

If my subject, my photo, comes out too dark, like the White Sands example above, I need to move my exposure compensation scale toward the + side. Plus means more and more means more light. It sounds counterintuitive, but think of it this way. Below is a crude scale of bright-to-dark.

                                                                       White/bright
                                                                               |
                                                                               |
                                                                    Gray or mid-tone
                                                                               |
                                                                               |
                                                                      Black or dark

The example of the grayish-looking white sand came out gray or mid-tone--See the scale above. 

The solution is to move my exposure compensation dial to the + side. To the overexposure side. But, that does not mean I am overexposing the white sand. What it does mean is I am overexposing from where the built-in exposure light meter took me--to gray or mid-tone. I wanted a photo of white sand. So, I did just that: moved my exposure compensation dial, in this case, to a +1 1/3 stops. And I got this result. See below. 
                                         

Now, that is white sand. The + 1 1/3 is not a magic formula. The amount of "overexposure" needed is based on how bright the subject is, the lighting on the subject, and how much space the white subject takes up in the frame. First, I estimate, make the adjustment, and look at the results. If, for example, + 1 1/3 is close but not quite there, I might go with a + 1 2/3. It's all about how I want it to look, not how it should look. It's about getting the right exposure, not the "correct" exposure.

Below are more end-result examples and the amount of exposure compensation I used to get those results.   
                                                                             +2/3                                                     

+1    

+1

+1 1/3

+1

+1
(I didn't want it so white that I would lose the details in the sand)

And here are the first two examples again, side-by-side.

          

     

Before I leave, let me say this about black or very dark subjects. The steps are the same, except in reverse order. I want a black or dark subject to come out that way. If it comes out too light, I will go toward the minus (-) side on the exposure compensation dial, to keep it dark or black.

So, please remember. If your subject is white or very bright, you're going to have a problem. Move that dial toward the + side until you get what you want. If your subject is black or very dark, you're going to have a problem. Move that dial toward the - side until you get what you want.

Now you won't go home with images that are too dark or too bright. 

Eli Vega

www.elivega.net

vegaphotoart@gmail.com