How to take good photos: 07 Get your camera’s ISO settings right
At its most basic, the ISO setting on your camera controls the sensitivity of the sensor to light: the higher the ISO, the more ‘sensitive’ the sensor, and the less light it will need to record an image.
However, it’s important to realise that changing your ISO doesn’t physically change the sensor.
More accurately, increasing the ISO amplifies the signal from the sensor; but, in addition to amplifying the image-forming part of this signal, it amplifies any non-image-forming elements as well.
The classic comparison is with a record player or cassette deck, where turning up the volume makes any background crackles, pops and hissing more obvious.
With a camera, this background interference results in a grain-like texture in your shots, referred to as ‘noise’: either chroma noise (coloured speckles) or luminosity noise (an overall texture).
Depending on the camera and the way it processes images, noise can range from being totally imperceptible at lower ISO settings to being so prevalent at high ISOs that detail is lost to the coarse texture, although it’s always most noticeable in mid- to dark-toned areas.
The simple rule of thumb is to use the lowest ISO setting you can. This will be determined by how much light you’ve got, what shutter speed and aperture combination you want to use, and whether you’re hand-holding the camera.
If you want to use a fast shutter speed and small aperture in low light levels, for example, you would, through necessity, need a high ISO, while a static landscape with the camera mounted on a tripod could be taken using a low ISO.
If you’re shooting in low light and don’t want to introduce excessive noise by cranking up the ISO, flash is a great solution, especially if used in conjunction with a slow shutter speed to record the ambient light.
Some cameras have scene modes specifically designed for this (Night Scene or similar), or you can shoot in Aperture Priority (Av) or Shutter Priority (Tv) – the majority of DSLRs will auto-balance the flash to the ambient light, so both your flash-lit subject and background are correctly exposed.
Don’t forget that you can use flash in daylight too: popping up your camera’s built-in flash can add an instant sparkle to a day-lit portrait, lifting shadows and adding catch-lights to a subject’s eyes.
What is ISO: camera sensitivity settings (and the best way to use them)
First camera crash course: simple solutions for mastering your new DSLR
Night photography: how to set up your camera to shoot anything
Black and white photography: what you need to know for perfect mono pictures
How to take good photos: 08 Take control of focus
Your camera likely has a fantastic array of focusing modes, and these get increasingly sophisticated with every new product launch.
Multiple AF points, and the ability to select them individually or in groups, means that for pretty much any shot you want to take you can tell the camera precisely where you want to focus.
However, this does mean that you have to tell the camera which focus point or points to use.
It’s no good setting your camera to choose an AF point for you, because it doesn’t know what you’re taking a picture of.
It may get it right most of the time, but other times it won’t, so taking control is the best solution.
Beyond the actual point you want to focus on, you also need to decide how best to use the AF system.
If your subject’s moving, think about setting the camera to its continuous AF mode so it maintains focus on the subject as it moves through the frame.
For static subjects, single AF is often quicker and more reliable.
Don’t forget that you can also focus your lens manually. If your camera’s struggling to get a positive lock on a low-contrast subject, don’t waste time trying alternative AF points – just switch to MF and focus where you want.
This is worth considering when you’re taking close-up or macro shots, because the depth of field is likely to be so shallow that it’s easy for your camera’s AF system to be slightly off.
Manual focus can also be invaluable to sports photographers, which might sound counter-intuitive given the speed of many AF systems, but sometimes they’re still not fast enough.
At a motor racing event, for example, a racing car might only appear in view for a split-second – long enough to take a shot, but not long enough for your camera’s AF to get a lock.
Instead, manually focus on a point on the track that you anticipate the subject will move to.
That way, when it appears you can take your shot without the delay of the AF trying to work out what’s going on.
Using hyperfocal distances
The hyperfocal distance is the optimum focus point for maximising depth of field. This point varies depending on the focal length and aperture you’re using, but when you focus at this point, everything from half the hyperfocal distance to infinity will appear sharp.
This makes it significant for landscape photographers who want to ensure they’re getting as much of the picture in focus as possible, even at the smallest aperture setting.
Use an online calculator such as www.dofmaster.com to work out the hyperfocal setting for every aperture on every lens you use, and note them down for quick reference.
Master your camera’s autofocus: which AF points to use and when to use them
Getting sharp images: every photo technique you need to know starting out
11 common lens errors (and how you can avoid them)
9 situations when autofocus will fail you