Lesson four: Master ISO

ISO is the measurement of a camera sensor’s sensitivity to light. Based on the speed ratings of conventional 35mm film (denoted as ASAs), most compacts, superzooms and DSLRs will allow photographers to alter the ISO setting while in Program, Aperture Priority, Shutter Priority or Manual modes. But why would you alter the ISO and what effect does it have on the image?

In its most simplistic terms, photos taken at lower sensitivities (ISO 100, for instance) will be less noisy than photos taken at higher settings (ISO 1600). This is due to the way the sensor gathers light. In brighter conditions, there’s lots of light around and the sensor doesn’t need to be as sensitive to light. When the light levels start to drop, the sensor needs to amplify its sensitivity. While this does help gather more light, it also gathers more noise and this is shown by a graininess within the photo at high ISOs. Noise is the term used to describe the grain and artefacts that appear in photos at higher sensitivities.

Similar to 35mm film, different ISO settings are suitable for different shooting scenarios. For instance, most cameras are set to ISO 100 by default, as normal lighting conditions should be around the 100-200 mark. Photographers can then utilise a low sensitivity of 50-64 (if available) for bright conditions and 800 and above for low-light conditions. Much like choosing the right film speed, choosing the right ISO can make the difference between a successful and unsuccessful shot.

In the last two Camera School lessons, we’ve talked about how aperture and shutter speeds work together to create perfect exposures, and the third element to this equation is ISO. If you don’t have enough light – when you’re shooting a wedding in a church, for instance – you can up the ISO to allow you to keep a faster shutter speed, but still achieve a good exposure.

Camera sensors work by collecting light into each individual pixel on its surface. How big the pixels are varies depending on how big the sensor is. For instance, a 14MP sensor in a compact will be a lot smaller than a 14MP full-frame or APS-C-sized sensor. This is why compacts typically suffer from more noise than DSLRs. The smaller sensors with more megapixels crammed onto a smaller surface mean smaller pixels, and these generate more noise.

It is important to understand how and why ISO works in order to manipulate it to ensure you achieve the best possible results. In situations like sunsets and sunrises, or interior shots of museums or churches, you’ll have little choice but to shoot in lower-light conditions. You’ll also be without the use of your flash, meaning your camera is your only weapon. By choosing a long shutter speed (1/2sec or over), a wide-open aperture (f2) and a high ISO (ISO 800 or more), you should be able to collect enough light to capture a successful shot.

If you do choose to turn your ISO off Auto, always check it before your next shoot. A whole day of clear blue skies and treasured memories can be quickly ruined by noise, which you may not notice until you load your images onto the computer at home.
 

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The shutter controls the duration of an exposure. In creative terms, it’s the shutter that determines how time is depicted: whether movement is frozen in time so that every tiny detail is visible, or blurred to create a sense of motion and energy.

A fast shutter speed will freeze movement to reveal detail, form and features. For example, in wildlife photography, a fast shutter speed reveals exactly how a subject moves – the position of its body, its legs, the intensity of its gaze. To illustrate this point, the image of the cheetah was photographed using a shutter speed of 1/2000sec. This fast shutter speed has frozen all movement, revealing how all four feet leave the ground and how the animal’s hind legs reach forward beyond the point of its forelegs.

Even for everyday photographic situations, such as when photographing a son or daughter during a school sports day, playing in the back garden or park or while on holiday, a fast shutter speed will capture the moment to best effect. And, when shooting action sequences of wildlife, sports or people, a fast shutter speed will ensure you never miss the moment.

Another benefit of faster shutter speeds is the reciprocal increase in lens aperture. As was explained in last month’s lesson, lens aperture controls depth of field, which, in turn, controls emphasis. Fast shutter speeds typically result in large apertures (eg, f2.8 or f4) and might help to remove distracting background detail that’s blurred to a point where it’s hidden.

Faster shutter speeds will also reduce the likelihood of image blur caused by camera shake, which can ruin an otherwise excellent photograph. At slow shutter speeds there is more of a chance of camera shake adversely affecting image quality, particularly when using telephoto lenses. While the very best solution to avoiding camera shake is to use a suitable tripod, this isn’t always practical.

Slow shutter speeds can be used creatively to blur motion and create a sense of movement. Keeping with the wildlife example used earlier, the image of wildebeests (shot at 1/20sec) reveals little in the way of detail, but creates a wonderful sense of movement.
Neither example – the cheetah or the wildebeests – is the right way or wrong way to take the photograph, but simply different interpretations of a subject.

A useful example that illustrates how shutter speed enables a photographer to alter a subject’s appearance is a waterfall. A shutter speed in excess of 1/500sec will freeze every droplet of splashing water from a tumbling waterfall, revealing the intensity and power of the subject. This is a very different effect than the ethereal look of water that’s created when it’s photographed at a slow shutter speed. Of course, what constitutes a fast shutter speed depends on the subject being photographed and is an important consideration, for two reasons.

First, the specific shutter speed needed to freeze movement is always relative to the speed of the subject. For example, a sprinting cheetah runs at such pace that a shutter speed of even 1/500sec is relatively slow, so a setting of at least two stops faster (1/2000sec) and possibly more is required. Conversely, a setting of 1/500sec might be fast enough to capture the action of a child playing in the garden.

Second, and less obvious, is a symptom relating to high-resolution (6MP+) digital cameras. Because these cameras produce such high-resolution images, for many fast-moving subjects (particularly wildlife and sports) a minimum shutter speed of 1/1500sec is needed to capture an image that is completely sharp to the naked eye.

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Lesson One: Master Your Camera

Deciding which camera to buy can be a minefield. There are so many models, manufacturers, features and prices, it can be hard to know where to start. Here at DCE, we believe you should buy the perfect camera for you, and not just the one that offers the most megapixels for your money.

Budget is usually the first consideration. Decide how much you are prepared to spend on your new camera, and stick to it. Budget will narrow your choice somewhat but £500, for instance,  can still buy you a beginner DSLR, prestige compact or a superzoom. £100, on the other hand, will limit your choices to compact only.

Next, decide what you will use your camera for. If you want it simply to catch quick shots on rare holidays, if you’re a keen snorkeler and want to shoot underwater or if you want to take stills and video of a new grandchild, you need to look out for different features.
The most common type of camera is a compact. These are usually small, slim and simple models, although the higher-end models are capable of great images and creative shooting. Compacts typically have small sensors and lenses which can impede image quality, as well as a high number of automatic and scene modes to help new photographers get great results.

Superzooms or bridge cameras are typically built to look more like a DSLR, with a large battery grip and a large lens. They have a long focal reach, utilising 10x or more optical zoom power – great if you need a camera covering everything from
wide-angle to extreme telephoto lengths.

DSLRs, or digital single lens reflex cameras, are usually more advanced, with larger sensors and interchangeable lenses that offer greater creative options for the photographer. They also offer viewfinders alongside LCDs as compositional tools.

Hybrid or system cameras have also just entered the market. They bridge the gap between compact and DSLR, offering interchangeable lens creativity and large sensors in a smaller, lighter and easier-to-use bodies without a DSLRs mirror system.

When looking for a new camera, many photographers look at the megapixel ratings first. Megapixels refer to the number of pixels on a camera’s sensor in millions. Larger numbers may seem better, but you also need to consider the physical size of the sensor.

Compact cameras typically have smaller sensors than DSLRs, therefore squeeze more pixels onto a smaller surface, affecting image quality.

Other features you may which to look out for include focal range. On a DSLR or hybrid, this will be dependent on the lens you buy. On compacts it will be represented by a figure like 28-120mm. 28mm represents to widest angle of your lens, and 120mm the telephoto end. The wider the range, the more zoom capacity the camera boasts.

Features like smile detection, video recording and scene modes have become must-haves on all current models and help add value to your new kit. Don’t to be swayed by them, though, unless they are important to your shooting needs.

After you’ve decided what you’re looking for, go to your local camera retailer and try a few models. Remember that photography doesn’t necessarily stop with purchasing the camera. Choose a camera that will suit you for the long-run and you’ll find it an amazing investment.

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Lesson two: Depth of field & Aperture

Lens aperture controls something referred to in photography as ‘depth of field’. Depth of field is a phenomenon caused by the limitations of the human eye. When a lens is focused, light is formed into a sharp point. However, light reflecting from other parts of the scene, closer to or further from the point of focus (ie, areas that are out of focus) instead forms blurry circles. The further from the point of focus, the blurrier these circles – and the relative part of the scene – become.

The resolving power of the average human eye enables humans to detect in a print roughly A4 in size, from practically any current DSLR camera, the presence of circles that are larger than 0.03mm in diameter. Anything smaller than that will appear as a point rather than a circle, and therefore appear sharp (in focus) to the naked eye.

Because of the way the human mind works, people are drawn to objects in a photograph that are sharp and ignore blurred objects. The blurrier the object, the more it is ignored. So, using lens aperture to alter the extent of depth of field enables a photographer to emphasise some objects (by making them appear sharp) and de-emphasise or hide completely other objects by blurring them.

Technically speaking, lens aperture is the hole in the diaphragm in the lens that allows light to enter the camera when the shutter is activated. This hole can be made smaller or larger by adjusting the aperture value using the Command dial on the camera (or, on
some older lenses, using an aperture ring on the lens). The smaller the aperture set (eg, f32), the greater the extent of depth of field, resulting in more of the scene appearing to be in focus.

In practical terms, a landscape scene often commands foreground to background sharpness, because everything included in the scene is important. Therefore, depth of field will need to extend over a wide distance, which dictates using a small aperture (eg, f16 or f22). However, when photographing a portrait, it is typically more important for the subject of the portrait to stand out against the background. In this example, a large aperture value (eg, f2 or f2.8) will help to isolate the subject by blurring background detail and will draw greater focus onto the subject in question.

Another reason to adjust lens aperture is to gain a reciprocal change in shutter speed. Aperture and shutter speed are inextricably linked, and any change in one setting requires an equal and opposite change in the other for exposure parity to be maintained (a photographic law known as the Law of Reciprocity). For example, if the exposure settings are 1/30sec at f22, then an increase in aperture to f2.8 (resulting in more light entering through the lens) would equate to a faster shutter speed of 1/2,000sec (to reduce the duration of the exposure), since more light equals less time (and vice versa).

This can be advantageous, for example, when the subject requires a faster shutter speed and light levels are relatively low – this might be a wildlife action shot taken in the evening when wildlife is more active, or a sports shot taken on a heavily cloudy day.
Conversely, it may be desirable to set a slow shutter speed on a bright sunny day, for example, to blur the movement of water over a waterfall. Setting a very small aperture will result in a longer shutter speed, achieving the desired effect.

Aperture values are far more than a set of numbers in an LCD panel or on a lens barrel. Understanding the effects of different apertures will lead to greatly improved photography and pictures that appear closer in print to how they were originally imagined in the mind. 

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We’re lucky enough to have some of the most beautiful scenery in the world in the UK, but taking great landscape shots that capture the beauty of a location isn’t often easy: as with most things in life, practice makes perfect.

Make sure you’ve got a camera with a decent wideangle lens. Although some compacts do offer wide-angle attachments, your best bet is to go with a DSLR and a good lens, as that also enables you to use filters to enhance your shots. One of the single most important pieces of equipment a landscape photographer can have (aside from a tripod of course) is a circular polariser. These
filters only allow rays of light through that are vibrating on a particular plane, meaning that, with a quick twist of your filter, you can rid your shots of unwanted glare and reflections on water, glass and other non-metallic surfaces, as well as deepening blue skies and making fluffy white clouds really ‘pop’. Circular polarisers also saturate colours, livening up foliage and adding to the overall impact of your image. Keep your aperture small (by selecting a number of f/8 or larger) to increase your depth of field, so you keep foreground and background detail in focus. Also ensure that you set your white balance according to lighting conditions; if it’s lovely and bright like this shot, set it to Sunny, but if it’s dull and grey, setting your white balance to Shade or Cloudy will help to warm things up a bit.

Circular polariser
Use this type of filter to deepen blue skies, make fluffy white clouds really stand out and to reduce unwanted reflections on water and glass surfaces. Be sure to choose a circular polariser, as a linear one can disrupt the metering and AF systems in DSLRs

Aperture
If shooting manually or in Aperture Priority mode, set your camera to use a small aperture (a bigger number) in order to increase your depth of field. When shooting landscapes, it’s best to use a smaller aperture, to keep a greater number of elements in focus in your photograph

Leading lines
Look for lines created by objects that help to lead the observer’s eye into the frame. In this shot, the path leads the viewer’s eye right up to the main point of interest in the frame: the lighthouse. When shooting your own landscapes, look for the same effect created by walls, paths and natural arrangements of rocks and shrubs

Clouds
Although a crystal-clear blue sky looks fantastic when you’re out enjoying the sunshine, it can end up looking rather dull and flat in photographs. Using filters to liven things up a bit can help, but you’d be amazed what a difference the odd fluffy cloud can
make. Clouds add interest to skies, and are worth looking out for when composing your shots

Rule of Thirds
Keep your shot nicely balanced by sticking to the Rule of Thirds. Use your camera’s in-built grid system to help you, or use your imagination to draw lines that divide your composition up into thirds, both horizontally and vertically. By placing elements in your
shot on the points where these lines intersect, you’ll produce a well-balanced shot that the human eye can ‘read’ very easily

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Ever noticed that you rarely see photos of lightning taken during daytime hours? There’s a very good reason for that – it’s virtually impossible to achieve. The speed and unpredictability of lightning means than you can only ever hope to get a shot by leaving the shutter open for an extended period. Only at night will the scene be dark enough to get away with this without too much light hitting our sensor.
There’s no easy way to shoot lightning, but there are some tried and tested techniques that should improve your chances of getting a shot. Firstly, use a tripod to keep a steady shot. Then set your aperture to f8, your ISO to 100 and your focus at infinity, with the autofocus off. If your camera has the ability to keep its shutter open indefinitely, select this setting, otherwise simply select the longest shutter speed you can. With the camera pointed in the direction of where the most lightning hits are occurring, your best chance to capture it is by holding the shutter open for a prolonged period to cover one or more lightning strikes.
Safety is paramount so never stand within five miles of the epicentre. Your tripod could conceivably act as a lightning rod so dress appropriately and stay near your car. In fact, why not shoot remotely from your car as a precaution?


The darker the better
You can only get away with shooting such a long exposure at night, so the darker the surroundings the better. You’ll have more luck away from the glare of a town or city.

Silhouettes
Your lightning photography will have more impact if there are objects in the frame to be lit up by the strike. In this image the tree-lined lake delivers silhouettes and a reflective surface to add more visual interest.

Keep it sharp
A decent lightning picture is impossible to achieve hand-held, so you will need a tripod in order to keep your photograph razor sharp. The more clarity the lightning bolts have, the better.

The sky’s the limit
The quality of your lightning picture will, to a large extent, be determined by the sky itself. Sometimes clouds will obscure the bolts so all you get to see is a general flash of light. There’s little you can do about this but you may need multiple attempts to get it right.

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Capturing a great action shot is one of the hardest things you can do with your digital camera. But with some patience and practise, images like this one are perfectly possible. Basically, the key principle you need to remember is that pointing your camera in a fixed direction and hoping to capture a fast-moving subject as it speeds past is a lost cause – your finger will simply not be fast enough. Instead, you need to pre-focus your camera onto the subject before you shoot by half-pressing the shutter button. This will save the time it takes for the camera to lock focus before taking its exposure.

Once you’ve done this you should follow the moving subject as it travels (a technique known as ‘panning’). Do so to ensure that the subject constantly remains in the frame. This will result in a blurred background, but that doesn’t matter – it all adds to the sense of speed. This technique should increase your chances of a good shot, but your most important tool – and one that’s available on most mid-range to high-end cameras – is the Continuous or Burst shooting mode. Selecting this mode will set your camera to capture a quick-fire series of shots (normally until the buffer is full) when you keep your finger pressed on the shutter button. Using this handy feature, the chances of at least one exposure being the perfect shot you’re after is significantly increased.

1. Panning
Pan your camera to follow your subject as it moves along. This will result in a blurred background, but this only enhances the sense of speed.

2. Zoom in
The bike in this picture is cropped in places, but it’s better to get a sharp close-up shot than to keep your camera at a distance. You don’t always need to keep the whole subject in the frame.

3. Pre-focus
Pre-focus your camera onto a specific point on your subject, such as the rider’s helmet, to ensure it remains in sharp focus, even if peripheral areas lose clarity.

4. Empty space
When framing your shot, ensure you leave an empty space in front of your moving subject for it to ‘move into’. This helps to enhance the impression of forward momentum.

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We all want great photographs of our kids that we can keep forever, but children aren’t always the easiest of subjects to capture. They’re so full of energy, it’s  mpossible to keep them still long enough to take a decent snap. The solution is just as obvious as the reason behind why they aren’t the easiest subjects – just don’t even try to keep them still! Not only are posed pictures difficult to achieve, they can also be rather dull and old-fashioned in appearance. It’s much better to snap your kids doing what they do best (ie making mayhem) as it captures  something of their unique energy and personality. Pics like these make for much  more vivid memories when you look back on your photos in years to come. So, treat photography as a game rather than a chore. Get your kids doing something they love, like riding a bike, and snap away while they’re in their element. Not only will this result in better pictures, it will also bring a smile to their faces, rather than a sulk or a glance in the other direction. Something we’re sure many  parents despair at when trying to take a photo! Don’t just take one shot either. A series of ‘action’ shots are far more likely to result in a great photo than one single attempt.

1. Keep ‘em busy
Your kids will be far more likely to cooperate for the camera if they’re doing something they enjoy. The trick is to make them forget that the camera is there. So, start up a game or get them riding their bike

2. Candid snaps
Often the best strategy is to keep the kids so occupied they don’t notice the camera. But in a shot like this, the picture has become part of the fun of the bike riding game, so the child has no problem in showing his smile for the camera

3. Fill the space
Kids are bold and full of life, so give your picture a bold framing too. Don’t snap from a distance, but take a shot that fills the whole frame with a beaming face. That way, your kid’s personality will shine through

4. Backgrounds
The angle of this shot is unusual but effective. By shooting from low-down, the photographer not only gives a dramatic perspective but also turns the blue sky into a cheerful but clean and uncluttered backdrop

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One of the most important aspects to get right when shooting silhouettes is proper exposure. To calculate this, you first need to position your subject between the light source and your camera. Set your camera to manual exposure and use an external light meter, or your camera’s internal meter (in Spot-metering mode), to take a light reading from the highlight area. Alternatively, try metering the background and then the subject. The difference between these two readings provides the right silhouette exposure. You then need to expose for the background only, so that everything in the foreground is recorded as being dark. Make sure you experiment with alternative white balance settings as well to warm up and cool down the colours in your photos, as these can have a great effect over the mood of your final image. You can also increase your depth of field by setting a small aperture, ensuring that you’ll have a greater range of elements in focus within your image. If you’re using slow shutter speeds, then a trustworthy tripod or other stable object is a must. If you can justify the cost, it’s worth investing in a good, sturdy tripod. At night, a bright, full moon can be a very effective ‘backlight’, as can artificially-lit fountains, street signs, or car headlights, for example. With bonfire season upon us, there should also be ample opportunity to experiment with nocturnal, al fresco silhouettes.

1. White balance
When shooting a sunset silhouette, make the most of the sky colour by taking the camera out of Auto White Balance mode. Try switching your White Balance mode to ‘cloudy’ or ‘shady’.

2. Subject
Concentrate on the subject’s outline when framing your shot, in order to achieve the best composition. Keep the background as plain as possible,making the shape of your subject the main focus.

3. Focusing
For the purposes of shooting silhouettes, manual focusing is the best way to achieve this, as the dark tones of your subject will result in your lens ‘hunting’ in Automatic mode.

4. Lighting
For maximum impact in your shot, always make sure there is as little light as possible falling onto the subject itself. Otherwise any detail will be recorded, spoiling the black silhouette effect.

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If your camera has a macro mode (or even better, if you’re lucky enough to win a macro lens), this is an excellent time of year to get up close and  personal with the natural world and pull off some fantastic close-up shots.

Don’t be put off by our exotic subject pictured below. You might not have geckos to photograph, but you’re likely to be able to find all manner of insects, frogs and slow worms in your back garden!

Once you’ve found your subject, mount your camera on a small tripod or rest it on a bean bag or other stable object and compose your shot. Selecting an aperture of around f/8 keeps the eyes and nose of the creature nice and sharp.

Having the background blurred helps the creature to stand out and will compensate for any distracting objects that you may be unable to move. If you can, shoot in RAW format, as this will give you more flexibility when it comes to editing your shots later. Practise the tips and experiment with ordinary tungsten lamps or bounced flash (remember to set your white balance) if conditions are somewhat dull. If you want to have a go at photographing more exotic creatures in controlled conditions, visit your local zoo or wildlife centre and ask a handler if you can get closer to some of the animals under their supervision, or check out one of the UK-wide wildlife workshops at www.wildarena.com.

1 Catch light
A great way of avoiding the ‘taxidermy’ look is to ensure there’s a catch light in your subject’s eyes. Think how much more dynamic and alive people look in portraits when the photographer has positioned the light source to create a catch light – the effect is exactly the same with other living creatures. You can achieve it by positioning your subject in natural light, or using off-camera flash.

2 Add depth
Avoid having a depth of field that’s too narrow; although this can be good for creating abstract images, when shooting creatures like this gecko, it’s desirable to have the eye(s) and nose pin-sharp, with the focus gently falling away in the background for added impact. If you can control your aperture, select a bigger number (small aperture) to keep more elements in focus, or a small number (large aperture) to have less in focus.

3 Directional lighting
Light fall-off on the background is desirable for macro shots, as it helps the subject to stand out. Experiment with the positioning of your light source in relation to the subject and try to avoid having it ‘square on’ – positioning your light source to one side creates shadows, adding contrast. Fill in any deep shadows with a reflector or a piece of white card.

4 Stay sharp
Aim for fast shutter speeds (1/60sec or faster) to freeze movement. If you don’t have a tripod, be inventive and find something else to rest your camera on; a table or a pile of boxes will suffice. To reduce the chance of camera shake further, use your camera’s self-timer mode to fire the shutter, or use a remote control or cable release if you have one.

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