This video tutorial explains what all the parts of the histogram are and how changing the exposure effects how it looks.
On my last photo walk I discovered that many people are still not using the histogram to check the exposure of their digital photos. They rely on the back-of-camera playback instead.
This is really not a good way to check exposure. Mostly, because it’s hard to see the playback when you’re outdoors on a sunny day. Plus, depending on the brightness of your LCD screen, it may not be all that accurate. Using the histogram is always best. This video tutorial shows the histogram in action.
As you learned from the video, the histogram is a graphical representation of the brightness in your photo. It is about the exposure values (Ev). Some cameras display the histogram as a single combined graph, and some cameras let you set it up for a 3-channel red-green-blue view, which shows you in more detail which parts of your image are over or underexposed.
- Some cameras display the combined version of the histogram (left) and some can display the red, green and blue channels separately (right).
People often approach digital photography rather sloppily, thinking they can fix everything in editing, but that takes time.
Every time you take a photo it’s a good practice to check your histogram to make sure your photo is not under or over-exposed. Then you can correct it in camera instead of in photo editing. This will save many of your photos, especially if you shoot jpgs. This can save you tons of time too!
The left side of the histogram represents the dark areas of your photo, the right side the bright areas, and the midtones in the centre.
How to fix the histogram if it’s not looking good
If the histogram is showing that your photo is over or under-exposed, you can use your camera’s exposure compensation feature to correct it. You don’t even need to know much about f-stops and shutter speeds to do it.
All cameras have exposure compensation features built in. Just look for the +/- button. When you press it, a scale with a range of -2 to +2 comes up. You can add or remove light using this scale. Each full increment is one Ev.
If your histogram does not go all the way across to the right of the graph, then you have an under-exposed photo. In that case you will need to add some light, or some exposure to it. You can do this by changing your f-stops and/or shutter speed manually, or you can use the exposure compensation feature and add light using the + (plus) numbers.
If your histogram shows over-exposure, or too much light and the graph is climbing the wall on the right side, then you need to remove some light from the scene. In general if only one channel is over-exposed, you usually have enough detail left to work with the file. For example: When you shoot a sunset, the red channel is typically overexposed, but the green and blue are fine.
To remove light from the over-exposed photo you can adjust your f-stops or shutter speed manually, or you can use the exposure compensation feature and remove light using the – (minus) numbers on the scale.
Do you check your histogram after every shot?
If you are shooting several photos in a row in the same lighting conditions, then you just have to check at the start of the sequence and maybe do a spot check once in awhile. I’m so used to checking the histogram all the time, that it has become an automatic thing for me. You might notice other photographers doing it too.
If you have any questions or thoughts on this topic, please let me know in the comments.
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