Explore Landscapes #11

Learning How to Trust your Histogram

Back in 2011 I attended a seascape/landscape photography workshop on the south coast of the UK in Dorset. The workshop was led by a wonderful photographer, Helen Rushton, who (at that time) specialized in seascapes and underwater photography.

Helen taught me three very valuable lessons that have shaped how I photograph today:

1. As far as possible (aka always) shoot seascapes and landscapes with your camera on a tripod.

2. How to use ND, ND Grad, and Polarizer filters.

3. Always trust your histogram when determining exposure.

Trusting your histogram is the focus of this post, and is an essential part of my workflow each and every time I take a photo.

Measuring Light and Determining Exposure

Metering is the traditional method of measuring the amount of light reaching your camera’s sensor - see Image 1.

• The center of the scale is 0 - where the camera's meter thinks the image is correctly exposed.

• If the pointer moves to the left (negative) it’s underexposed.

• If the pointer moved to the right (positive) it’s overexposed.

A histogram can be displayed during shooting (on mirrorless cameras) or be reviewed after shooting (on DSLRs) - see Image 2.

• The histogram is a bar graph that shows the 256 different tones from pure black (on the left) to pure white (on the right).

• The height of each bar shows the number of pixels that appear in the image of that tone.

• It is far more accurate than relying on camera metering, which is far more accurate than relying on the camera’s display screen.

• In Image 3 the histogram butts up against the right hand edge indicating that some of the whites are clipped, however, the meter shows a correct exposure. If you relied on the meter you would have taken an overexposed image where there would be no detail in the clipped area.

As you (or the camera) change your exposure settings (depending on the shooting mode you are using, for example Program, Aperture Priority, or Manual) the histogram will change shape and move to the right or left - see Image 4 and 5.

By using the histogram you can adjust the camera settings that affect exposure (aperture, shutter speed and ISO) to ensure you capture the full range of tones in the scene.

• The intent is to position the histogram so that the graph profile touches the bottom and does not get clipped on the left-hand or right-hand side.

• This ensures that you don’t have any blown-out areas (pure white) or detail-free shadows (pure black).

• The shape of the histogram is not important, and is purely a result of the different tones in the scene that you’re shooting.

Sometimes, such as when photographing sunrise, sunset, or other high contrast scene, it is not possible to position the histogram graph without clipping the whites, blacks, or both.

This is because the dynamic range of the scene (the difference between the brightest and darkest parts of the image) exceed what the camera’s sensor can capture in a single image.

In this case, you can use a technique called exposure bracketing to take a range of images with different exposure settings. These bracketed images are then combined in post-processing to create a final image which shows the full dynamic range of the scene.

I’ll discuss this technique in my next post.

If you have any questions on my workflow or any other topic I've mentioned, please leave a comment below, and I'll get back to you.

Until next time, explore, experience, and enjoy our wildlands responsibly. Think before you geotag. Adopt the 7 Principles of Leave No Trace and practice Responsible Nature Photography.

Bye for now,
Jon