The Exposure Triangle - what is it and why do you need to know? (Cheshire photography course with Picture It Big)

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If you've started to wander off the AUTO setting on your camera and are having a play with the Aperture (Av / A) or Shutter (Tv or S) setting, you'll have noticed that when you alter one, the other changes at the same time. This is because they work together to make sure that your picture will be correctly exposed.

Just in case I've already used a bit of jargon that's confusing, let's cover that off first.

The obvious question you might be asking at this point is why would you change the aperture or the shutter speed, rather than let the camera do it all for you on AUTO? Well it puts you in control of the type of image that you take, rather than pointing and shooting, you are determining the outcome and can get creative. Probably the whole reason you splashed out and bought a bridge or SLR camera rather than sticking with a compact. (Some compact cameras do allow you to set the aperture and shutter speed and all this applies to those too!)

So, first of all, why would you want to change the aperture? Have you ever wondered how you get that amazing soft focus, blurred areas in a photograph, whilst the point of focus is still completely sharp, like in the picture of the baby? Aperture, that's how! Set a low aperture like f/2.8 (which crazily is a big opening in the lens) and you'll get a lovely soft background. This makes your subject stand out nice and crisp and opens up a whole world of creativity. This is also called a narrow or shallow Depth of Field.

If you set a high aperture number like f/16+ then your image will be in focus from front to back. Typically you might do this with landscapes. And whilst you're in control of the aperture, your camera is setting the right shutter speed to get the exposure right.

So, what about shutter speed? This is how long the opening in the lens is open for and it can be anything from the tiniest fraction of a second through to several seconds. If you select a fast shutter speed any movement is frozen - anything higher than 1/500th of a second is considered quite fast. Slow shutter speeds blur movement and can be used to great creative effect. If you use a slow shutter speed - anything less than 1/60th of a second, you need to rest the camera on a flat surface or use a tripod to avoid camera shake.

I started off this blog by saying that aperture and shutter speed work together to get the right exposure. In order for a picture to be correctly exposed the opening in the lens needs to let in enough light onto the camera sensor. If you have selected a small opening, then it needs to stay open longer than if you selected a large opening - simple isn't it?!

But sometimes there simply isn't enough available light to do what you want to do. A situation I've faced a number of times is photographing a child running along a forest path, where the overhead canopy of leaves has reduced the amount of light. The camera is on its lowest aperture setting (biggest opening in the lens), but the shutter speed is still too slow to freeze the child's movement. I don't want to use the flash as it's so flattening and it wouldn't reach the child anyway. But there's another option available to me, thank goodness - the third part of the Exposure Triangle, the ISO setting.

ISO determines how sensitive to light the camera's sensor is. In the olden days of film (!) you could buy reels of film that were more or less sensitive to light and your digital camera's ISO setting is the equivalent of this. The higher the ISO number, the more sensitive to light. So in nice bright conditions you use a low ISO number - 80-200 and in duller conditions you could use a higher one like 800+.

When you use a high ISO number you will find that your shutter speed increases - yay! The only downside to high ISO numbers is that you can get a grainy effect in your images. It depends on your camera how pronounced this is. Top end cameras handle high ISOs well, whereas compact cameras can be notoriously bad. If you leave the ISO set on AUTO the camera will decide what to do for you. Call me a control freak but I prefer to know what it's doing!

So there you have the three settings that make sure your pictures are correctly exposed:

Aperture
Shutter Speed
ISO

And I've even created a handy Exposure Triangle diagram to help you remember it all!

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I can bring all this to life for you in a bespoke one to one photography class, tailored to your requirements. To find out more or to book click here.

By Jane Burkinshaw. Share this post by clicking on one of the Share buttons on the right hand side. I'd love to hear your comments too!

Is AUTO only for beginners (and what the heck is"P")?

“Oh, I never take my camera off AUTO”. A very frequent comment when I talk to people about their photography. Usually said with an air of slight embarrassment as if it’s something to be ashamed about. They would be pleasantly surprised and reassured to hear that I often have my camera on an AUTO mode (although I use the P automatic mode – more on that later). I have lots of gadgets and machines in my home that offer a variety of settings and I only use one all the time – the dishwasher springs to mind. If I choose the ECO setting it does what I want it to and I feel good that I’ve done something slightly environmentally friendly. I know there are faster and hotter settings, salt rinses etc but I’ve never bothered to work out how to use them and I don’t really care as long as my dishes are sparkling. It’s like that with a camera – as long as AUTO allows you to take a good photo and get the result you want, you don’t need to go off piste and try the other settings. So it’s fine to set your camera to AUTO, but it's better that it’s a conscious decision rather than the only option.

Regular readers of my blogs (I fool myself into thinking there are a few!) will be familiar with my views on technological knowhow versus the role of opportunity and having a natural eye. You could know how to use every setting on your camera but still be unable to spot a good shot or perhaps not even have the camera with you when a great shot presents itself. Taking a good picture relies primarily on being in the right place at the right time, an ability to see that something before you has the making of a good image and having your camera at the ready. In many instances these elements will be sufficient and so will having the camera set to AUTO. However, there are situations where the automatic setting cannot get the best results and if you haven’t got other options then you won’t get the optimum shot. You may have already experienced the frustration of spotting a great photo opportunity, only to find that the shot is blurred or wrongly exposed, despite the fact that your camera has previously delivered great results for you.

LIGHT – or not enough of it may be the cause of the majority of your problems when using the camera on AUTO. The camera automatically sets the shutter speed to suit the available light. On a dull day or in deep shade it will use a slower shutter speed to let more light in. This can mean that although the resulting photograph will be correctly exposed any movement may be blurred or the whole picture may suffer from camera shake. Your camera is quite clever and knows this and will decide to fire the flash to provide some extra light. This might not give you the effect you were looking for as flash can be quite harsh or unflattering. If you take the camera off the AUTO setting you would have a number of options available to you, to stop the flash firing and increase the amount of light coming into the camera without slowing down the shutter speed too much. Setting a larger aperture (lower F number) with the AV (aperture value) setting or increasing the ISO would probably work.

You might be thinking that this is not particularly relevant for you but there are lots of circumstances where you could come across dull light conditions during the day. I have done several shoots in woodland areas and have found that the canopy of leaves reduces the light to such an extent that my subjects are blurred if they are moving e.g. running, waving, even just walking. Flash can just kill the atmosphere and make the background appear unnaturally dark. Using other camera settings has enabled me to still get the shot I was looking for.

Another common instance when you might benefit from moving off AUTO is when you are photographing something or someone against a cluttered background. If you are zooming in on the subject then the background will start to blur but you can control how much it blurs and how much your subject stands out by using the AV setting and using a larger aperture (lower F number).

Taking the camera off AUTO and knowing what setting to use instead puts you in control rather than the camera. When I use an automatic setting I make a conscious choice rather than using it because I don’t know what else to try.

Note that I said “an automatic setting” not the AUTO setting. You may not be aware of it but your camera is likely to offer a semi-automatic mode called P or “Program Mode”. In this mode you can make some of the decisions for yourself and make some corrections. For example you decide when to use the flash – it doesn’t fire automatically. You also have the option to make the picture lighter or darker using something called Exposure Compensation. And you would also be able to change a number of other settings whilst still letting the camera automatically set the shutter speed and aperture size.

It can be quite scary when you go off piste (off AUTO) for the first time, but what have you got to lose? If you make a mistake you can delete it and try again. I experimented with the AV setting by propping my foot up on a stool one day and taking pictures of my big toe with different apertures! Needless to say you won’t find those shots on my web site! And try the TV (time value) setting to increase and decrease the shutter speed with a moving subject – I have lots of photos of blurred running dog progressively becoming in focus running dog!

Not sure about apertures and shutter speeds? Forget your manual, it’s unlikely to help you and sadly neither will many of the magazines and books which claim to be guides to digital photography. In my experience they all assume a certain level of knowledge and tend to jump in at quite a technical level. The best quick introduction I’ve found is in Annabel William’s book “99 portrait Photo Ideas” where she tells you just enough to go out and have a go. Then once you’ve had a play around and grasped the basics that’s the time to start looking at the books and delving in a little deeper.

It’s easier to practise these settings outside in daylight, so do a bit of reading in the evening, use the Quick Set Up Guide, which hopefully came with your camera, to learn how to change the AV and TV settings and then get out with your camera during the day. And don’t forget that AUTO is there for a reason – it will give you a good shot in many circumstances – but go on, be a devil, try the P setting sometimes too! You’ll soon find that you’ll be using that in preference to AUTO and before you know it you’ll be flicking onto AV and TV too.

By Jane Burkinshaw. Share this post by clicking on one of the Share buttons on the right hand side. I'd love to hear your comments too!