Understanding Histograms
Coming home after a long day of shooting and finding out that you have a bunch of either overexposed or underexposed pictures has got to be the most frustrating feeling for any photographer.
At that point, you probably feel like chucking your memory card straight into the trash is a better option, rather than painfully looking through your ruined pictures and seeing if there is anything left to salvage.
But of course you don’t do that. You take a deep breath, re-open the folder with your destroyed photographs, and begin looking for a way to fix this. That’s the life of a photographer.
But it doesn’t have to be.
Let us introduce you to histograms - the tool that most new (and some old) photographers ignore.
What are Histograms?
A histogram is an intimidating looking graph that shows how many pixels are exposed in the image you just captured. When used correctly, it can help you to set the correct exposure and get a beautifully lit shot. Sort of like light meters, but not quite.
While the built in light meter will help to set your settings to have optimal exposure while you shoot, you need to learn how to read and understand histograms - they are the best way to check if the picture is well exposed after you shoot it, as you can see above.
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So How Do You Read Histograms?
Histograms read the tonal values of your pictures and display the results in a graph. On the far left of the graph, you have the black tons, and on far right are your whites. Everything in between are midtones.
When you glance at your histogram, you want to see a nice bell shape starting just before left edge and ending just before the right edge.
If the line is touching any of the sides, it means that you are either losing detail in your shadows or your highlights (depending on the side). When you see this happening, you can use exposure compensation to correct your exposure and take another shot.
Understanding and Using Exposure Compensation
When your histogram is too far left, set your exposure compensation to +0.5. This should bring the shadows up a tiny bit and save your detail from being lost.
If it is still touching the side, you can either go further with exposure compensation or adjust your shutter speed and aperture.
When the lines are touching the far right side, try setting exposure compensation to -0.5.
Get more details about using exposure compensation in the video above by Matt Granger.
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Exposing to the Right
A popular technique when using histograms to shoot is purposefully exposing your images so that you have more information on the right side of your graph. This way you overexpose the image, but not so much that the highlights are blown out and detail in shadows can be brought back in post production.
Although it sounds great in theory, there are some downsides to this technique.
When bringing back lost detail from the shadows, you introduce more noise into your picture, and in most cases, this is not a good look to have.
Even if it is what you were going for, it is better to introduce noise in post production instead, and have a crispy clear original image.
In fact, when you use histograms, the best practice is to have most of your information in the midtones. This way you have all the detail that your camera can capture and more creative freedom when editing the pictures.
Be Mindful of What You are Shooting
Reading histograms and preventing them from being clipped (cut off on either end) at all costs is a good technique, but what if the scene can be improved with some clipping?
Part of being a good photographer is the ability to always be mindful of your subject and what surrounds it.
So if you are shooting a very brightly lit scene, like the one shown above, there will obviously be more details in the highlights.
For example, when you shoot in the studio with white backdrop, you always aim to overexpose the background to achieve that pure white. On the histogram, this would show as clipping and you might be tempted to correct your exposure, but doing that would actually ruin the lighting of the scene.
See what I mean?
At night, or in low light conditions, you will have a lot of information in your shadows.
Again, on the histogram it would show up way to the left, and while it might look bad at first glance, in reality, this is the result that you should be going for.
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All of the Pros, None of the Cons
Histograms are an essential tool for learning and understanding how your camera works and how to shoot with different lighting.
In fact, histograms are so important in photography that you will have them displayed in Lightroom and Photoshop by default since they are just as important when editing as they are when shooting.
Over time, every photographer develops their own way of taking pictures. Some use histograms only as reference when setting up, some glance at them after each shot, and others don’t use them at all. There is no right or wrong here really, as long as you are achieving the results that you want.
However, it is crucial to at least have a clear understanding of this tool’s purpose and use. Should you be using it, though? It’s entirely up to you.
Learn more about histograms in the video above by Tony and Chelsea Northrup.
