Exposure Compensation And Bias Are Your Friends – Photography Basics

Photography Basics - Understanding Shutter SpeedI have some bad news.

Your camera is not perfect.

Don’t worry though, none of them are. The saving grace to this dilemma is the Exposure Compensation (sometimes called Exposure Bias) feature on DSLRs, smartphones, mirrorless cameras, drones and a lot of point and shoot cameras. It is a little button that looks like this.

Exposure Compensation And Brighter Things

Exposure Compensation

The exposure compensation button works by forcing the camera to over expose or under expose, according to its current settings, by a set number of stops. Hence the symbol for it is the + and – signs.

Typically the range is -3 to +3 stops but some cameras will have a -5 to +5 range. Cameras are pretty similar in how the setting actives; simply press or hold down the button and then turn one of the camera dials. On phones you will typically tap the screen to set exposure then drag up or down to change it.

Your user manual explains exactly how your exposure compensation feature works.

How Handy is Exposure Compensation?

Exposure Compensation can be helpful when you know your camera is going to mess up or is already messing up. As explained in the Metering Modes post, your camera is not perfect and can only meter a limited area of the view. Plus, your camera has to make decisions about what’s important in the frame and try to make everything come out all average. But it makes mistakes.

We’ll use an image of a tugboat on Puget Sound from Seattle as an example of a challenging shot where exposure compensation helps.

Program mode, ISO 100, f/11, 1/500 – The camera is doing all the exposure calculations here:

Exposure Compensation and other fun things
This is with the camera’s default setting using evaluative metering. I could switch to spot metering and point it at the tugboat. Instead, I use a camera dial to selectively over expose by one stop.

Over Exposing

Here’s the same shot over exposed by one stop.

Exposure Compensation and other fun things

Getting better. The tug is a little more visible.

Below are shots over exposed by two stops and then three stops.

Exposure Compensation and other fun things

Exposure Compensation and other fun things
As the exposure gets higher and higher, we can see the tugboat more and more, although we lose detail in the background.

I chose this image because these types of decisions come up all the time when shooting sunrise or sunset.

Now For Under Exposing

Swinging the other direction, we’ll under exposed by one, two and three stops.

Exposure Compensation and other fun things

Exposure Compensation and other fun things

Exposure Compensation and other fun things

We get more detail in the clouds lit by the setting sun, but we lose our main subject along the way.

As you can see, there is a big difference in exposures across a swath of seven stops of light (-3 to +3 stops). What is most pleasing to some, in this case, might not be pleasing to others.

How is it Useful?

The over/under exposure compensation is a quick way to correct your camera’s wrongheaded bias towards too harsh or too dull of light. In this example, the shot that was underexposed by one stop has a good chance of being salvaged and enhanced in a computer.

This quick setting can also help insure faces aren’t hidden in darkness by shadow when all around them is bright light. It’s better to blow out the details in the surroundings than leave a face too dark.

On Your Phone

To use exposure compensation on a phone, tap the screen and move your finger up or down to over or under exposure. It’s super easy.

Tomorrow we’ll cover Histograms!


Questions?  Pop ’em like Pez in the comments section below. or email me at peter@peterwestcarey.com.

Photography Basics – A 43 Day Adventure, and its companion 40 Photography Experiments, are series written by professional photographer Peter West Carey. The series are designed to unravel the mysteries of photography, helping you can take better pictures. Subscribe here to receive all the updates and bonus material. Your comments are always welcome.

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2 Comments Exposure Compensation And Bias Are Your Friends – Photography Basics

  1. Paul Weimer October 17, 2018 at 4:49 pm

    How do you feel about the theory that overexposing and clawing back the exposure level in LR or other post processing software is safer and better than underexposing?

    Reply
    1. Peter Carey October 17, 2018 at 11:40 pm

      In a technical sense, I have seen evidence that there is a slight, very slight, improvement to that method. For my Canon, I am happy with the noise control it has and prefer to start lower. To me, it gets to be a level of granularity, or pixel-peeping, that only matters most when hitting extremes most of us don’t encounter.

      Reply

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