Poor Man's Photo Diary: Exposing to the Right

[Originally posted on 12/23/2018]

First of all, if you don’t have a basic concept of photography exposure. At the end, this might be more confusing than helpful. And this is not to despise the beginners at all so I promise I will come back to the basics of exposure when I have time.

In the old days when everyone was still shooting films, the number one rule is not to overexpose the film. Because if you under expose the picture, you still have a chance to save the picture during the darkroom process but if you overexpose the film. There is almost no way to recover it. The difficult part of film photography is during the shooting, there is no way to know if you over or under expose the film. So when in doubt, we might underexpose the film a little bit to be on the safe side.

Now in digital era, the exposure information can be easily and instantly accessed through a powerful and yet simple tool - the image histogram. If you look at the histogram, X-axis is for tonal variation, a fancy way of referring to the brightness. Y-axis is for the number of pixels. Basically it means the lefter, the darker the righter, the brighter.

A complete curve in the histogram

There is more to say about histogram but for now, you just need to remember the ultimate rule when you shoot: keep your complete curve within the histogram. Note that, this doesn’t mean the picture is perfect. It just means from exposure point of view, the picture has a chance to be adjusted to be perfect, nothing to do with composition or creativity.

The next word related to histogram is “clipping”. Clipping is bad so you want to avoid it. Clipping can happen in both highlight and shadow areas. Clipping is when your curve on the histogram got cut off.

The curve got cut off on the darker (left) side

Take this histogram as an example. This is a histogram generated by Canon software. The histogram only uses the middle 4 big rectangles so you can see the curve didn’t get to finish on the dark (left) side. So we say there is a clipping on the dark end. What it means is that there is a dark area in the picture which will be pitch black, none of the details will be shown on the picture so that’s bad!

Next time when you take a picture, you might want to pay attention to the histogram. Because it actually provide you a piece of more accurate exposure information than your screen.

Stay tuned for Part II.