Photography Basics {How does a camera work} | Photography

In 2015 I completed my Diploma of Photo Imaging at the Nepean Arts & Design Centre, graduating with Distinction in every subject. It was a fabulous learning experience for me, and has really taken my photography to the next level. One of the things I enjoyed was the excellent teaching and instruction from the photographers generous enough to give their time. It's something I would love to do myself one day, and so I thought why not start on the blog.

It's always logical to start with the basics of something, and it's no different here. I want to teach you the basics of photography, and how to get the idea of your image out of your head and through the lens. To do this, we need to start at the very beginning. We need to know

How does a camera work?

At it's core, photography is all about light. You need to make sure your camera is capturing the light just right so that your photos aren't underexposed (too dark) or overexposed (too light). There are 3 elements that work together to make sure you have just the right amount of light in your photograph: Shutter Speed, Aperture and ISO.

When you adjust one setting you also need to adjust the other settings to make sure that the right amount of light hits your camera's sensor to produce a properly exposed photo.

Before you start learning about the whys of these settings though, you first need to understand how a camera works. Having an understanding of how a camera works will go a long way towards helping you understand why changing one setting affects the other settings and how your picture turns out.

What is ISO?

In old-school film cameras, an image is created by exposing a piece of film to light. In digital cameras the film is replaced by a sensor. The sensitivity of your sensor can be adjusted by changing the ISO setting on your digital camera. In old school terms, different films had different sensitivities, or ISO ratings. If you used a film that was more sensitive to light, then you could take pictures in low-light situations that still turned out well.

This picture was taken in a restaurant with very low-light so I boosted the ISO on my camera to try and compensate.
In an ideal situation I would have had my tripod to allow for a slower shutter speed
and lower ISO to be used, as the high ISO has introduced noise to the image.

Do you remember the Kodak ads for camera film on the TV? Or the numbers that were on the boxes of film you bought, usually 100, 400 & 800? The ads boasted about how good 400 film was for taking pictures of your kids blowing out their birthday candles or playing sports. That 400 film had way more sensitivity to light than say the 100 film, so a picture of a kid blowing out candles on their cake would be much brighter with 400 film than with 100 film.

Back before I started learning about photography and had a dSLR camera I had a Point & Shoot film camera and I had no idea what those numbers on the film meant. I just always bought the bigger number because it was meant to 'perform' better.

Well, those numbers were an ISO rating and as I said above, they affected how sensitive the film was to light. In the same way, your camera's ISO setting determines how sensitive your camera's sensor is to light. So if you're taking photos in a low-light setting, you can increase the ISO so that your sensor becomes more sensitive and picks up more of the light.

But how does the light get in to your camera and reach the sensor in the first place?

The diagram below shows how light gets in to your camera and where the different bits and pieces are.

{Image credit}

As you can see in the above illustration, the first thing the light passes through is the lens, which is where the aperture lives.

What is Aperture?

The aperture looks like this...

{"Aperture diaframma" by CelinaTH - Own work. Licensed under CC BY-SA 3.0 via Wikimedia Commons.}

And works like this...

"Apertures" by Chinneeb - Self-made using Image:Aperures.jpg. Licensed under CC BY-SA 3.0 via Wikimedia Commons.

As you can see in these pictures, the aperture can open up wide to allow a large amount of light to get through to the sensor, or it can close down small to let less light through to the sensor. Depending on how open or closed your aperture is you can control two things. The first thing the aperture controls is how much light gets through to the sensor. The second thing the aperture controls is your photo's depth of field, the area of your picture that is in sharp focus.

Once the light passes through the aperture it then has to pass through the shutter to reach the sensor. This is where shutter speed comes in.

What is Shutter Speed?

The shutter in your camera is a set of doors that open and close when you press the button to take a picture. Depending on how fast or slow you set your shutter speed, the sensor is exposed to the light for a shorter or longer time.

A fast shutter speed means that the doors of the shutter open and close very quickly, which means that the sensor is exposed to the light for a shorter amount of time, resulting in darker photos. When the shutter speed is set slow, then the shutter doors stay open for a longer amount of time, allowing the sensor to be exposed to more light, and creating an image that's lighter.

Putting it all together

So by changing how open or closed our aperture is, and how fast or slow our shutter doors open and close, we can control how much light hits the sensor that creates the image. With these two elements working together, and by choosing how sensitive we want our sensor to be to that light (ISO), we can control the way our photo turns out, or are exposed.

Once you understand how these three elements work together to create a picture, you can begin to experiment with changing these settings yourself. The easiest way to start is by setting your camera to either Aperture Priority mode (meaning you change the aperture setting and the camera automatically chooses the shutter speed and ISO for you) or Shutter Priority mode (where you choose the shutter speed and the camera automatically chooses your aperture & ISO for you).

Once you start experimenting in this way you'll quickly start to see how different settings affect the exposure of your photos. You'll also start to notice three other things that are affected by Aperture (depth of field), Shutter Speed (movement) and ISO (grain/noise).

Considering how long this post is already though, I will save the more detailed explanations of Shutter Speed, Aperture and ISO for my next post. In the meantime, have a play around with this awesome camera simulator I've embedded at the end of this post (if it works! If it doesn't you can find it here - http://www.camerasim.com/apps/camera-simulator/ ).

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Anyway, I hope this info has been useful in helping you understand your camera a little better. I find it really hard to explain this stuff and have massive respect for the photography teachers out there who are able to break it down so well without confusing people. I hope I haven't confused anyone! I truly believe that if you understand HOW your camera works you will then have a much better understanding of why different things happen when you start to experiment with manually changing your settings.

Cameras are amazing things, and don't get me wrong, you can take great photos in Auto mode. But cameras are essentially a 'dumb' device, they don't have a brain and they can't read your thoughts. If you want to have more control in creating the image you've imagined in your head, then you need to learn how to control your cameras settings manually, and it really is easier than you think!

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