This post was last updated on August 17th, 2014
On the back of your camera there is a brilliant little graph that many first-time DSLR owners have no idea what to do with. It looks like this:
Please excuse the quality of these images as I am photographing the LCD of my DSLR using an iPhone :-p
This my friends is called the histogram and it is one of the most important tools a photographer can learn to use to assess what your camera has recorded. On DSLR cameras you can find the histogram while reviewing your images. On my Nikon 7100, I press playback and the up button to view the histogram along with some other details. Grab your cameras manual to figure out where yours is.
The histogram essentially shows you the data your camera has recorded from a particular image on a graph going from black to white. The left side of the graph shows pixels (the tiny dots that make up your image) of your photo that are completely black. The right side indicates completely white.
The “ideal” histogram (image graph) will be a bell curve with the most information in the center and less information on the edges toward complete black and white (left and right sides respectively). Of course the game changes when you’re shooting in low light, silhouettes, snowy scenes ect. so lets just stick to the basics for now. Avoid having your curve shift to the right or the left side; a bell curve is best.
Here are a couple examples:
This was a photo I took of staff at a hotel. The lobby was dimly lit so my photo came out a little dark. The histogram is showing that a lot of my information has been recorded on the black (left) end. Some of the pixels have become so dark that the curve has been pushed “out of bounds”. This means that those pixels are completely black and resulted in the photo being underexposed. It’s not necessarily bad to have all black pixels, but it was certainly not my intention to have so many in this photo.
Now here’s another example but on the other end.
Totally wasn’t paying attention on this one and snapped a picture that was super bright! You can see all the information on the graph has slammed into the far white (right) side of the graph and nearly the entire picture turned out white. This is called overexposure.
You can control exposure a couple of different ways, like using aperture, shutter speed, ISO and exposure compensation. If you aren’t familiar with these terms, don’t worry – we’ll be diving into exposure and how to control it later on.
So, recap. “Good photos” typically have a bell curve where most of the information is spread out between the left and right sides of the graph area. Now let’s interpret another histogram of the beautiful blue waters from Isla Holbox.
This histogram is so smooshed in the center that it has risen over the top of the graph. The tone is all focused smack dab in the middle. This histogram is telling us that the photo has hardly any contrast. There isn’t a huge difference between the lights and darks in this photo. This photo isn’t very interesting, anyway. Referring to our last lesson on composition, if I add a subject or take into account the rule of thirds, the contrast might spread out naturally. It’s not always bad to have low contrast photos, but it is something to be aware of.
In some situations the ideal curve will be unattainable:
This occurs mostly when shooting into the sun or shooting during the middle of the day. As you all should know the sun is bright. Well, your camera has a hard time seeing the sun too when it’s so bright; as a result your sky will nearly always be completely white during midday. This midday bright sunlight will also create dark shadows. In this photo I had the problem of a very bright sky and a very dark and shady foreground. This is called a high contrast situation. For these situations it’s better to come back later in the day when the sun is less intense and contrast between light and dark is slightly reduced. Alternatively, you can use your camera’s HDR setting to combine an overexposed and underexposed photo. Again, we’ll talk more about that in exposure, but at least you have an idea. The takeaway here should be avoid shooting into the sun or at midday to avoid the histogram above.
So by just glimpsing at your camera’s histogram, you can decipher the information your camera has picked up from an image – most importantly the spread of white vs dark information. Of course, understanding your histogram while taking photos will also make the post-processing much easier.
Next time we’ll go over how you can shift your histogram so you can better control the look of your pictures.
Do you utilize the histogram while photographing? Any questions you’d like to see answered next time? Any and all comments are welcome :-)
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~ Natural Light: Explains the different qualities of natural light and how to use them to your advantage.
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~ HDR Photography: Explains what HDR is and how to use it.
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