Light & Composition

A great deal of photography comes down to understanding how to control the light hitting the film or sensor of your camera. Cameras increasingly control this for you if they’re left in automatic mode. That is a good thing in many situations but knowing how to take control of these choices will open up another world of options for you.

Manual Mode

Nothing beats using a camera in manual mode to figure out how it works but it also helps to have a basic knowledge of what’s going on. That varies a bit between camera types but it’s all about controlling how much light comes into the camera for how long. Mechanically, the aperture controls the size of the hole that lets the light in and the shutter controls the amount of time the light is allowed to shine through. You can also control how sensitive the film/sensor is to light through the ISO. The lower the ISO number the less sensitive and the less grain.

Screenshot of the Canon DSLR interactive tool.Canon has a pretty impressive interactive tool that lets you adjust aperture, shutter speed, and ISO to see what the impact is on your images.

Until recently camera phones had fixed apertures and dealt with light by controlling just ISO and shutter speed. That changed recently with the release of the Galaxy S9. It’ll be interesting to see how this impacts other cell phones in the near future. Cameras in general are starting to reach new levels of complexity with models like light that capture images with multiple lenses on multiple sensors resulting in more data than was possible previously. This kind of capture will allow for fundamentally different post-processing options.


With aperture your options are constrained by the mechanical limits of the lens itself. Aperture size is measured in f-stops. The lower the number, the wider the aperture. Lower/wider apertures let in more light and also result in a shallower depth of field. Usually, lenses with wider apertures are more expensive. You may see/hear people refer to lenses with large apertures as ‘fast glass.’ I do not approve of this choice but you might as well know what they’re talking about.

You can see a shallow depth of field below with the chicken being in focus and the man and background blurring. It was shot with an f stop of 1.8. That blurring can be seen as a benefit or an issue depending on your goals. When it’s a good thing, people will often call it bokeh. While in macro photography, people are usually battling to create a greater depth of field through focus stacking or other methods.

catching chickens flickr photo by bionicteaching shared under a Creative Commons (BY-NC) license

Shutter Speed

Experimenting with shutter speed will open up interesting opportunities and allow you to take photos in scenarios that would otherwise be impossible. Long exposures also let you create images that blur moving elements in ways that can be interesting. The shot below was a 4 second exposure at f/11. That gives a greater depth of field and allows for the blurring of the lights as the ride spins during that time. You’ll see a similar technique often used on waterfalls or at beaches where the water blurs in surreal ways.

Waiting for the wheel flickr photo by Sky Noir shared under a Creative Commons (BY-NC-ND) license


There are a variety of ways to think about composing your images. The most import aspect is that you are thinking about composing your photographs. We’ll breakdown some of the more common patterns below.

Guideline of Thirds

We won’t go so far as to make it a ‘rule’ but consider concepts like ‘the rule of thirds’ as tools to get you to think about composition.

Wikipedia tells me that the rule of thirds was first coined in the 1790s by John Thomas Smith. So this one has stood the test of time. You’ll see other people arguing for the golden spiral or even dynamic symmetry.

Gestalt Theory

Word Bank