Everyone should know this when using a speedlight!

Updated: Jul 14

When starting out, flash photography can feel a little overwhelming. However, as with most things, it's only scary to start with. Once you get stuck in then things will start to make sense.

Today we want to explain what affect changing your shutter or aperture setting has when you turn your speed-light (flash) on. The simple answer is that they will affect the way the ambient light in the room and the light from your speed-light behaves in the scene.

Let's consider the shutter speed first. The shutter speed controls the ambient light. Take a look at the following images...

They are all taken at f5.6 and the only change is the shutter speed. As you can see, the slower the shutter speed the more you can see in the background, in other words the more the ambient light in the scene comes into play. While there is hardly any change in the exposure of the subject this ambient light does throw a warm cast onto them which prevents the image from feel devoid of colour, or feeling flat.

The aperture on the other hand controls the exposure of the subject.

Here we kept the shutter speed the same and only changed the aperture. As you can see, the exposure of the subject increases as the aperture opens up. There is some lighting of the background but this is due to the spill from the flash in a small room. Had the shot been taken in a large room the spill of flash would have been less noticeable.

If you need to change the exposure of the subject you now have two options, you can play with the flash strength or change the aperture. This is good to know, especially if you need to preserve your speed-light's battery life then you'll want the flash strength to be as low as possible. You can then use the aperture to allow more light to fall on the subject instead.

We hope that this blog has helped further your understanding. Now you need to experiment and try different settings. We suggest only making one change at a time and try to predict the outcome. When you find you are regularly predicting the outcome correctly then you can be fairly sure your understanding of this principle is in place.

If however you are still struggling and need some help then head to our search page here where you can look for a flash photography course near you.


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