How to Properly Expose Your Photos Using the Histogram
The first step to any great photograph is obtaining the proper exposure in the field. Getting the shot just right in the field is the key to allowing yourself to have the most freedom in post processing to achieve the look and feel you are going for in a particular photograph. Dialing in the exposure is a constant balancing act between shutter speed, exposure, and ISO. I stress how important is it to get the correct exposure to all of my students because it's something that you can't go back and fix. You can always go back and fix a bad edit or dust spots on your lens, but a poor exposure is something that you have to go back and reshoot. Even if you feel like your editing skills aren't very advanced, focus on getting the exposure right in the field so that later down the road when you do feel confident in your edits, you can go back and re-edit your photo.
This blog post is going to be outlining how I expose all of my photos perfectly using a technique that many photographers call "Exposing to the Right" or "ETTR". This technique is achieved by using the histogram.
What is a histogram?
For photography purposes, a histogram shows the light values of the image as a whole. The histogram is displayed as a graph, and each pixel in your photo represents a spot on the graph. The lightness value of each pixel is then stacked onto the graph, and the histogram is output. This allows you to see how light the pixels in the image are, with the right side of the histogram representing pure white (100% lightness) pixels, and the left side represents pure black (0% brightness). This is important in photography because any pixels you capture in the field that are on the very end of the right or left side are essentially gone for your editing purpose. Any pixels that are pure 100% lightness will remain white, no matter how bright or dark you make the image, and anything that is on the very far left will remain black. Luckily, anything in-between can be brightened or darkened to bring back detail or to get rid of detail in the scene.
Why does this matter for my photography?
You want to keep your histogram off of the edges whenever possible, as this will ensure that you retain the best possible version of your photo for editing. However, this is unavoidable in some scenes. Occasionally, you'll find that the photos you are taking may contain too much dynamic range, meaning that your histogram is touching both the far left and far right side of the graph. In these cases, you'll have to choose to either underexpose or overexpose the scene. In most cases, I always recommend underexposing, meaning that you'll accept the fact that the histogram is touching the left side of the graph. To dial in your exposure, you'll want to continue to darken the scene until the histogram is no longer touching the right side. This will allow for the brightness pixels to still be editable and still contain detail. This concept is referred to as "Exposing to the Right".
How do I Expose to the Right?
When you're in the field, you'll want to make sure the histogram is showing on your camera. Most cameras allow you to do this while toggling through the different view modes, which show things like the in camera level, settings, and more. If you use a DSLR, you'll need to go to live view in order for this to work. On a camera like a Sony Mirrorless, you're always in live view by default. Eventually, you should get to one that has the histogram on the corner of the screen. Once you see this, it's time to dial in your exposure. You'll notice that as you change settings, the histogram will move. Keep darkening the scene by increasing shutter speed, closing down the aperture, or decreasing the ISO until the histogram is no longer touching the far right side. I've included a photo below to show what the histogram of one of my RAW files looks like.
Learning to dial in your exposures takes time and practice, but it's the first step you must take in order to create amazing photos. If your photo doesn't have high dynamic range, such as a photo taken in the forest during flat light, you likely won't need to use the histogram, but it's still good practice to do so. The times where you'll find the histogram to be most useful is in photos like the one above, where you have darker foreground elements as well as a bright sky. If I opted to forgo the use of my histogram, it's likely that I would have blown out the sky, or lost even more detail in the shadows. Scenes like this require your exposure to be absolutely perfect in order to retain the most details, and ultimately create the best possible photo.