Why You Should Stop Using Your Histogram (Camera Lesson 29)
Summary: Ryan reveals three reasons why you should stop using your camera’s histogram to judge exposure in filmmaking.
Length: 3:49 minutes
The histogram is one of the most popular in-camera exposure tools. However it is also one of the least effective exposure tools that you can use for video. In this video I’m going to show you why the histogram is your worst enemy.
What Is Correct?
Take a look at these three histograms. By looking at these graphs, can you tell me which one is properly exposed? If your answer is that they are all properly exposed, then you’re right. Even though they are completely different, they are all correct. And that is the first reason why histograms are not a useful tool for exposure. They tell you how many pixels fall along the luminance range, but not anything specific about those pixels- like if that is really where those pixels should be falling or not.
There are some tricks that you can use to help you expose your image, like if it is a darker scene your histogram should be stacked more to the left. If it is a brighter scene, it should be stacked more to the right. But how much to the left and how much to the right? That is not very clear if you are only using the histogram.
An even bigger problem with histograms is that if that is the only tool you use to expose your images, you’ll end up with images that shift in exposure from shot to shot. There is a popular practice, especially with RAW cameras, to use the histogram to help you expose to the right. What that means is that you are allowing more light into the sensor, which is a good thing, as your image will be cleaner.
However, it’s a bad thing, because your exposure is now going to change from shot to shot as you expose to the right. A wide shot will typically have more content in it, which means a greater contrast range, and more highlights. Then as you move into tighter shots, there are less highlights, so according to ETTR you change your exposure to compensate.
This is a problem for three reasons. You now have several shots that don’t match which means you have to spend time in post correcting the images to match. And that is an added expense in time and money.
The second reason this is a problem is that as you adjust each shot, the noise levels will change which can be distracting and makes the scene feel less cohesive.
And most importantly, in my opinion, you are not communicating a specific look or vision. If your footage gets handed off to someone else to grade, which one is the look you intended? They have multiple looks to choose from and will just choose what they think is best. Which may or may not be what you intended. To be a strong visual storyteller, cinematographer, or filmmaker, you need to have a clear vision. And you can’t do that if your exposure and the look of your images are changing every time you change to a different shot.
If you are working by yourself and you have the additional time to correct your images, and you like to spend that time correcting you images on a shot to shot basis, and you don’t mind the change in noise levels, then you can keep on using the histogram. If, on the other hand, you need to hand your work off to someone else, or you want to spend less time fixing your images and more time on the story, or on finessing them, then I’d encourage you to look at using other exposure tools like the waveform or false color, or even a light meter, which I covered in the previous videos.
I do realize that sometimes you get stuck using the histogram for whatever reason. Which is why in the next video I’ll share with you some best practices that you can use to ensure consistent results when exposing with your histogram.
As always, if you have any comments or questions, leave them in the comment section below, and then come join me in the next video.