what is exposure: a crash course and a useful guide

Exposure. What a key element of photography and one of the first key technical details for any photographer to get their head around. But what exactly is it?

Exposure relates to the amount of incoming light [to the camera]. A camera controls exposure in two ways:

– the shutter: A camera’s shutter blocks all light from the cameras sensor until the moment you depress the shutter button. The shutter then quickly opens and closes allowing light to interact with the camera. The length of time the shutter is open and thus allows light to enter can be controlled by changing the shutter speed settings.

– the aperture: This is a hole which the light passes through as it travels down the camera lens. This can be thought of like the pupil in your eye. The f-stop controls the aperture opening and thus will affect the exposure.

So the manipulation of the shutter settings and the cameras aperture will determine the amount of exposure on your photographs. So how do you manipulate these settings and what effect does it have on your photos?

Shutter speed

Shutter speed is measured in 1/1000 of a second. The longer the shutter speed the more light that enters the camera. Therefore a 1 second shutter speed lets far more light in then a 1/1000 of a second.


so the f-stop controls how much light is allowed to pass through the lens. Below is a sample table, with the smallest f-stop at the top, working down to the bottom. The higher settings in the table thus show darker exposures:







The f-stops near the bottom of this column thus allow much more light into the camera, just as a wide pupil allows much light into a human eye.

so what is exposure?

exposure is the combination of shutter speed and f-stop settings on your camera. These settings can drastically affect the quality of your photos. for example the background can blur (especially at longer depths) if the aperture is small (such as f-2.8). In the same example closer images will be in closer focus, but the light settings may cause motion blur.

learning the art of exposure in far greater detail

I thoroughly recommend the following book to help you learn more about the fine art of manipulating exposure.

Understanding Exposure: How to Shoot Great Photographs with a Film or Digital Camera

The above book is available from Amazon for £10.31 (rrp £18+). It was first published in 2004 and at 160 pages it can be seen as something of an ‘exposure bible’. Bryan was also the author of the best-selling ‘learning to see creatively’ which you may have read?

This book has a great knack of making you ‘get it’. Even if you have read a many photography books and have got a decent technical understanding, this book works great in summarising aspects, which in turn ensures you throughly understand it when you have finished.

If you are just considering playing around with the automatic switch turned off, then i definitely advise you to take a look at this book, if only to help build your understanding!

~ by onlinecamerawarehouse on June 6, 2010.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

%d bloggers like this: