I thought I’d write this short and hopefully straightforward article to explain the basics of photography in a way that makes sense to me. There’s a lot of information out there that explains all of this in much more detail but I’m the kind of person who likes to be out there implementing techniques rather than spending ages reading about them, so I’ve tried to keep this as concise as possible. 

‘Seeing’ the Shot

You’ve got to put a little effort and thought into what you’re going to shoot before you even pick up the camera. Your eyes have such a wide field of view and can quickly adjust to all kinds of lighting situations but as a photographer you’ve got to learn how to see the world through a camera lens. Unfortunately you can’t be taught how to ’see’ a shot – that’s entirely up to you. But if you shoot something that interests or excites you then hopefully that will be conveyed in the picture.

There’s a quote by Marcel Proust that I try to incorporate in my approach to photography “The real voyage of discovery consists not in seeking new landscapes but in having new eyes”. For example, there’s a road right next to Glasgow airport that I must have driven along a hundred times before. At one point there’s a break in the trees that run along the side of the road that opens up to look over some farmers’ fields. Thankfully the day I finally noticed that, taken in isolation, the view of the fields was actually quite nice I had my camera in the back seat. I stopped the car, grabbed my camera and took the shot on the right. Now I’m always on the lookout for a shot that I might have missed previously.

The best way to understand what makes a good shot is to study (not copy!) other people’s work. If you see a shot that you like try to understand exactly what it is about it that you like. Is it the subject matter, the mood, the colours, the expressions, the composition? But most importantly – get out there, snap away, critique your own shots and quickly you’ll begin to understand what works and what doesn’t.

Composition

Once you’ve found your scene, you should take your time (if possible) to photograph it in such a way as to do it justice. Again, this is entirely up to you – there isn’t a definitive compositional method that is guaranteed to work. If you shoot digital then there’s no excuse for not trying out different angles and focal lengths to see what works best for that particular shot. A good starting point is to follow the ‘rule of thirds’.

If you imagine that your picture is divided by two equally-spaced horizontal lines and two equally-spaced vertical lines then your important compositional elements should be placed along these lines or their intersections. Looking at my shot of the Empire State Building in New York, you can see that I’ve placed the building along the left vertical line and the top of the building at the top left intersection.

If you’re shooting landscapes it often works well to place the horizon along one of the horizontal lines or if you’re shooting portraits try to place the eyes at one of the intersections. But remember that rules are made to be broken and so don’t worry about putting the subject smack bang in the middle of the frame if that’s what works best for that particular shot.

Let’s move on to the three things that affect exposure – aperture, shutter speed and ISO…

Aperture

Aperture is the size of the lens opening that determines the amount of light that reaches the sensor (or film). The diagram opposite shows typical f-numbers (or f-stops) found on most lenses – f/3.5, 4.5, 5.6, 8, 11, 16, 22 and 32. Each of these numbers lets in half as much light as the previous number.

Small f-numbers represent large (or wide) apertures and large f-numbers represent small apertures. It feels like that’s the wrong way round, but you’ll soon get the hang of it. If there are no other variables then the larger the aperture, the more light comes in and so the more exposed (or brighter) the image will be. That makes sense because if you use the analogy of a room in your house then the larger the window (i.e. the opening), the more light gets in and so the brighter it is. Similarly, the smaller the aperture, the less light hits the sensor during any given time and so the darker the image.

The same logic applies if the overall exposure of the image doesn’t change. So, the larger the aperture, the more light comes in and so the shutter doesn’t need to be open for as long (i.e. you can use faster shutter speeds). And vice versa - the smaller the aperture, the less light hits the sensor during any given time. This is why you sometimes hear an f/1.8 or f/2.8 lens being referred to as a ‘fast’ lens because they have large apertures, let a lot of light in and so allow for faster shutter speeds.

Aperture also controls the depth of field (i.e. the amount of the image that is in focus) and can allow for some creative focusing techniques to be used. The larger the aperture, the shallower the depth of field and so less of the image is in focus. The smaller the aperture, the greater the depth of field and so more of the image is in focus. It’s often preferable to have a greater depth of field for landscape pictures so that the entire scene is razor sharp. If you’re taking portraits though, you might want to blur the background to ensure that the viewers’ focus is entirely on the model.

Shutter Speed

This is the amount of time that the shutter is open and again determines the amount of light that reaches the sensor. Shutter speeds are measured in seconds or, in most cases, fractions of seconds. In daylight you’ll usually find that your shutter speed is anything faster than 1/60 sec but longer exposures at night can run into several seconds or even minutes. A shutter speed of 1/100 sec will let in twice as much light as a shutter speed of 1/200 sec.

If no other variables change then the faster the shutter speed, the less light hits the sensor and so the darker the image will be. Similarly, the slower the shutter speed, the more light comes in and so the brighter the image.

Shutter speed is important for capturing movement. A fast shutter speed will freeze the subject (so that it looks still) whereas a slow shutter speed can make it look blurred as the subject moves (creating a sense of movement). The slightly odd picture on the right was taken using a shutter speed of 1/160 sec and you can see how it has captured the water mid-flight. Compare that to the shot below left which has a shutter speed of 496 seconds and shows the star trails as they move across the night sky. It always amazes me what fantastic colours you can get from slow night exposures that your eyes just don’t pick up.

Getting a fast enough shutter speed is also import for avoiding camera shake (i.e. where the picture is blurred due to camera movement). Of course, one way to avoid this would be to use a tripod so that the camera is completely fixed; however, this isn’t always possible or practicable. As a general rule of thumb to avoid camera shake you should use a shutter speed with a denominator which is larger than the focal length of the lens. So, if your focal length is 100mm then you should have a shutter speed of at least 1/100 sec to avoid camera shake. If you’re lucky you might have a camera or lens that has vibration reduction (that’s what Nikon calls it – Canon calls it optical stabilisation and other manufacturers call it something else…) which means that you can use slower shutter speeds before camera shake becomes an issue.

ISO

ISO in the digital world is the sensor’s sensitivity to light. So, the more sensitive the sensor is, the less light the camera needs to get the same exposure and vice versa. Most cameras’ ISO settings range from ISO 100 to ISO 1600 or ISO 3200. ISO 200 is twice as sensitive as ISO 100 and so if nothing else changes, the ISO 200 picture will be brighter.

Why would you ever want to change your ISO? The main reason would be because you wanted a faster shutter speed, so you would increase the ISO so that the sensor didn’t need as much light to hit it. Conversely, you might want a slower shutter speed (to blur movement, for example) and so you would make the sensor less sensitive so that more light would have to come into the camera.

But something has to give when you increase the sensitivity and that’s noise (or, in film terms, grain). The higher the ISO the more chance you’re going to get of introducing or increasing noise. That’s fine in some situations where it can add a gritty or moody feel to your picture, but if you’re looking for a nice clean image then you should try and use as low an ISO as you can.

Bringing it all together

I’ve written about aperture, shutter speed and ISO as three separate elements and mentioned what would happen to the exposure of an image if only one of them was to change. While it is important to understand each of these elements separately, it’s perhaps more important to understand how they interact with each other. The easiest way to learn that is to play about with the dials on your camera and you’ll quickly begin to understand how increasing the aperture will increase the shutter speed and so on…

For example, if you increase the shutter speed by one stop (e.g. from 1/100 sec to 1/200 sec) then you’re letting in half as much light into the camera. To compensate for this you would need to either increase the aperture by one stop (e.g. from f/8 to f/5.6) or choose a faster ISO (e.g. from ISO 100 to ISO 200). Unless you’re using manual mode, your camera will chose these ‘other’ values to compensate for any changes you make, so you don’t need to worry too much!

Enjoy!

If you’ve reached this far in the article then the chances are you’re not a pro photographer (at least I hope you’re not) and so I think it’s safe for me to say that the single most important thing about your photography is making sure you enjoy it. Now go out and take some pictures!