Tame your DSLR with these 3 controls: Aperture, Shutter Speed and ISO

The word Photograph literally means: ‘drawing with light’. It is all about how much light hits your sensor or frame of film. Your camera controls the amount of light with essentially just three controls. When you are on Auto mode, your camera takes a best guess at what you are trying to achieve by striking a compromise between all three – and sometimes gets it right. But often the compromise doesn’t get you the image you had in mind.

Why should that be? Well, each of the three controls manages the light in different ways, so you get different effects from them. And today I want to talk about how each control affects your image, and how they can be used together to give you full control over your camera. Your manual will show you how to access each of them. Let’s start with a diagram:

Exposure Triangle

Exposure Triangle

The exposure triangle is about balancing ISO, Aperture and Shutter Speed. and I’ll talk a bit about each in turn.

ISO (100-6400)
ISO is about how sensitive your sensor (or film) is to light. And it works like this: if the light is bright then you need to reduce the sensitivity or your image will be washed out. So on a bright day you might use ISO100. On an overcast day you want a bit more sensitivity so you increase it to around ISO400. But if you are in a museum where it can be quite dark, and you are not allowed a tripod, you probably want to push the sensitivity up high to, say, ISO1600 or ISO3200 so you can use a faster shutter speed and not shake the camera. But there is a trade-off. the higher the sensitivity, the more your camera picks up on hot spots in the sensor  which leads to noise on your image – coloured speckles. If you are photographing a live concert that noise might actually add atmosphere, so don’t let it worry you. What does ISO stand for? ISO is a pseudo acronym for the International Organisation for Standardisation – or some might prefer International Standards Organisation as it rolls off the tongue more easily.

Aperture (f/numbers)[Av]
Aperture is about your lens, not the sensitivity of the sensor. Aperture is how wide open or otherwise is your lens. Inside your lens, behind all those glass bits, is a mechanism the operates a bit like the iris in your eye. And this iris mechanism opens or closes according to how much light you want to flow through. A wide open aperture gives you more light and a shallower depth of field (in other words your subject is in focus, but the background is blurred out – great for portraits!). But a closed down aperture is better for landscapes as it keeps just about everything in focus.

The F number is given as a ratio of focal length divided by the diameter of the opening. So it works like a fraction. For this reason the F numbers seem to go in reverse – f/2.8 is wider than f/22. But it makes sense if you think of it as f/2.8 is like just over 1/2  and f/22 is like one divided by 22 – which is very narrow indeed!

Shutter Speed (60sec – 5000 sec) [Tv]
Shutter speed controls the amount of time that light is allowed to fall on the sensor. A fast shutter speed lets in less light and is good for freezing action – great for sporting events or just to catch a person in mid air during a jump. A slower shutter speed gives you motion blur – which is great for silky waterfalls, smoothing out ripples on a pond, or to express speed, such as panning with a car so the background is blurred, giving a sense of motion.

If you are holding the camera in your hand, then a good rule to avoid camera shake is to set your shutter speed no slower than the focal length of the lens. So if you have a 50mm lens then your slowest should be 1/50th of a second, but if you have a 300mm lens then your slowest setting should be 1/300th of a second. Any slower then you should be using a tripod.

Aperture controls depth of field, shutter speed controls motion, and ISO controls noise. These three settings will give you complete control over your camera.

I’ll deal with the P, Av and Tv modes in a later post. And thanks to Barbara M from Wales (UK) for suggesting that I write on this topic 🙂

Let me know in the comments below if any of this is unclear – I’d love to hear from you 🙂

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How do you photograph quilts?

Tearing your hair out trying to photograph your quilt? Just remember that bald photographers have a real problem with reflections… But there is another way! And you are not alone – textiles are one of the most difficult subjects to photograph, and with a few tips and tricks you’ll be getting much better images.

And it’s not about the camera – whether you use  a point-and-shoot or a high end DSLR camera, or even your phone – they are just a means to get light onto a sensor. It’s all about the light.

The key thing is to get your light as white as possible (hence daylight globes) and as even as possible. The way to get even light is to disperse it with something – you could even use light tissue paper as long as you don’t set fire to it (that gets embarrassing to have to explain to the fire department [don’t ask…]) or you could invest in a couple of cheap ‘soft-boxes’ from your favourite online store or online auction house. What are soft boxes? They’re just lamps with a collapsible reflective shroud and a translucent front cover designed to soften the light so you don’t have harsh shadows. To give you a ball-park figure you’re probably looking at around $100 for a set of 2-3 soft-boxes.

The next thing I’m going to suggest is to turn off your camera’s flash. Flash is harsh light, and it will wash out your colours while bouncing reflections off anything shiny. A good way to think about it is to take a hard rubber ball and hurl it at a flat cement wall – it hurts when it bounces back at you! So now I’m bald, lightly toasted and with a black eye… But if you take a large soft beach ball and do the same thing, it doesn’t hurt so much because you are spreading it over a wider area. Light is like that.

By softening your shadows you can get more detail into your image.

Another aspect to controlling the light is to make sure that you only have the light you want – and that is where a backdrop comes in handy. You could pin up a sheet, or you may be lucky enough to have a large white wall inside, but if you’re like us, the walls are covered in distracting patterns and colours – in our case, books. Even if your textile is quite thick the light can be reflected around onto your subject and generally be a distraction. So a back-drop – in this case a backdrop on a frame can make a big difference.

Here is the set-up I used:

Quilt shoot - behind the scenes

Quilt shoot – behind the scenes

The trick is to light evenly and to try not to mix different kinds of light – because that can lead to all kinds of issues trying to get the white balance to work right. [You can see here that I didn’t correct the white balance for this behind-the-scenes photo]. The backdrop is primarily to prevent uneven lighting due to the busy background.

The soft boxes use a standard household flouro low-energy globe – which give a nice white light (especially the daylight ones) Have you noticed that when you take a photo with those lamps you sometimes get a greenish cast to your photos? The reason is that the way they work is they actually flicker 50 times a second in line with the mains power source – which is way too fast for your eyes to see, but can catch out a camera!) This can happen if you leave your camera on auto – it happened to me many times before I worked out what was going on.

But there is a solution which helps get better photos – and that is to use a low ISO (around 100) which gives you a longer exposure time (try using the ‘night’ setting). If you are comfortable with manual settings I’ll give you the settings I use at the end.

If you are using slower settings you will need to be able to keep the camera very still – so I suggest using a tripod if you have one – or at least a firm surface, and a remote trigger – or you can use a 2 second delay which means you don’t have your hands on the camera when you take the shot.

It seems like a lot to think about, but really it comes down to:

  • control the light (turn off the flash)
  • keep the camera steady
  • have a plain background
  • Stay calm.

If you are comfortable with manual settings I used:

  • Aperture: f/22 ( for depth of field)
  • ISO (sensitivity): 100
  • Shutter speed: 1.5-3 seconds

Let me know in the comments below how you photograph your quilts – or what sort of problems you encounter in trying to photograph them – or other textiles.


Perfect morning at the sump

Weston Ponds

Weston Ponds

So the sun rose majestically over the hills above Canberra. I rose to meet it on my regular morning walk and was not disappointed. Here we are in winter, frost on the ground and a few wisps of fog clinging to the valleys. And the water birds were happily swimming on the Weston Creek sump. It is officially called: ‘Weston Ponds’, but the reality is that this is a hole in the ground dug to receive stormwater from all the neighbouring drainage ditches. So it’s a sump. a beautiful, magnificent, picturesque sump. And the dawn was wonderful!