The Photographer, Histogram & Exposure Compensation

March 25, 2022March 25, 2022

There are two camera functions I constantly make use of, exposure compensation and my camera histogram. If you never use exposure compensation or check your camera histogram, then you are leaving getting the optimum exposure for a scene to chance!

We use our camera’s meter to evaluate the brightness of a scene and set our exposure for the scene. The camera histogram provides us with a visual representation of the overall brightness of the scene we are photographing. The histogram can also show when our images are under or overexposed, or when the contrast of a scene is too great for us to get an exposure that maintains the highlights as well as the shadow detail.

Evaluative Light Metering

I use a Lumix G9, which has a 1,728-zone multi-pattern sensing system for multiple/evaluative metering. It analyses my image by scrutinising the whole image, looking for the brightest, darkest and midtone parts of my image, it then averages out all of the readings to provide me with an exposure based on my shooting mode and ISO setting.

Here you can see that for this scene the camera was set to multiple metering (1,728-zone multi-pattern) and Aperture Priority. At ISO 200 and an aperture of F8, the camera metered the scene and set 1/80s as the recommended shutter speed. comparing the histogram and the scene together, I am happy that my exposure is optimal for my purpose and that no part of the scene is under or over exposed.

Camera Histogram

Using evaluative or multiple metering is a good way to get an overall exposure for the scene or subject you are photographing. However, on its own it is not enough, you must also consider your own creative or artistic intent and make use of your camera histogram. You use your camera histogram to assess the overall brightness and contrast of a scene and to decide whether or not you need to add some exposure compensation or not.

Here the brightness of the sky has led to this photo looking dark. Looking at the histogram we can see that it has more dark tones than light tones, it needs some exposure compensation. The histogram is pushed to the left and we have lots of dark tones (the under-exposed buildings), very few mid-tones and some bright tones, the sky, but the sky is looking more like a mid-tone as our image is underexposed.

Because this image was a RAW file, I have been able to apply exposure compensation whilst post-processing the file, it actually needed two stops of exposure compensation. Ideally, the exposure compensation would have been applied at the time of capture. Many photographers shoot RAW so that they can adjust exposure while post-processing. I think it is always better to try and get your exposure correct whilst shooting though!

Compare the two histograms, in this shot, we have now evened out our exposure and our histogram is more balanced.

Exposing your Subject or Scene

When it comes to exposing your subject or scene, you have to be able to judge two things for yourself,

The contrast range of a scene or subject
- Is the contrast range of the scene beyond the dynamic range the camera sensor? This is where the histogram comes in, learn to use it to evaluate the overall contrast range of the scene.
- If the contrast range of the scene means that you will lose hightlight and shadow details you will have to decide how to expose the scene
  - Expose for the highlights (add some minus compensation – less exposure)
  - Expose for the shadows (add some plus compensation – more exposure)
  - Shoot HDR
  - take two images 1) exposed for the highlights 2) exposed for the shadows and then blend the two images when post editing your files.
  - Keep the suggested exposure, knowing that the brightest parts of your image will be pure white and the darkest parts of your image totally black.
  - If possible come back when the lightighting conditions are less contrasty.
The overall brightness of a scene or subject
- This is where exposure compensation comes in to play.
  - Do you need your scene or subjet to be
    - darker? Add some minus exposure compensation.
    - Lighter? Add some plus exposure compensation.

Exposure Compensation

When you meter a scene your camera will suggest an exposure setting based on the overall brightness of your scene or subject. It is up to you, the photographer to decide whether or not the suggested exposure is optimal for your needs. If not, then you need to apply some exposure compensation or think about how best to capture the scene.

When things are happing fast we do not always have time to evaluate our subject or scene. If we are shooting JPEG and our exposure is off, then it’s hard to correct this in post-processing, so learning to always check your histogram is a must. If you shoot RAW, you can always apply some exposure compensation when post-processing but it is good practice to get your exposure right in camera and be a ‘Thinking Photographer’.

I hope this helps you get better exposures from your camera, always check your histogram and apply exposure compensation as necessary.