Switching to manual

The point of Auto is to make sure your image is correctly exposed – that means the highlights aren’t too bright and shadows aren’t too dark. Three factors affect this – your aperture (the size of the opening through which your camera sees the world), the shutter speed (the amount of time the shutter stays open) and the ISO (in the old days this was the speed of the film, but now it refers to the light sensitivity of the image sensor).

Take the plunge

If you’ve arrived at a DSLR or compact from a smartphone, you won’t have had to worry about any of these settings before, and in Auto mode your camera will handle them all in much the same way that your smartphone does. However, break away from Auto and all sorts of creative opportunities open up.

Aperture

Playing with aperture settings enables you to control depth of field, effectively deciding which areas of your image are in focus. This means that when you’re shooting wildlife or people, you can have your subject pop out against the background by keeping them in sharp focus while blurring what goes on behind them. That’s what Hilmy Ramadhan (instagram: @hilmyramadhans) has done with the shot of a watch.

You could also use the same effect to photograph an animal through the bars of a cage in such a way that the animal would be in sharp focus but the bars would be so close to the lens that they would blur enough to disappear from the shot. Both effects are achieved with a wide aperture (small f/stop number).

Using the reverse, a narrow aperture, you can get your scene in focus from front to back. This comes in handy for close-up or macro photography but it can also be used in landscapes, as in this shot by instagrammer @fredrik_stroemme.

The great American landscape photographer, Ansel Adams, recorded the country’s national parks using a narrow aperture like this as he believed everything should be in sharp focus. But that’s the great thing about manual settings – it’s up to you how you want to do it.

Shutter speed

Shutter speed affects your image in other ways. Put your camera on a tripod and use a lengthier shutter speed, and you can show motion in your shot. Great for showing light trails from car lights as in this shot by Sepp Rutz, but also good with water – transforming fast-moving waterfalls and waves into ghostly enigmatic scenes.

Being able to set your own shutter speed means you can catch fast-moving events, too. If you’re photographing birds or wildlife, and you want a perfectly focused shot showing the animal in action, you need your camera to be fast enough that there’s no blur.

ISO

ISO ultimately controls the quality of your image. A high number means the sensor is more sensitive to light so the shutter doesn’t need to stay open so long. It enables you to get shots in low-light conditions without using a flash. But there’s a downside to this, too. The higher your ISO, the more noise will creep into your shot. Some cameras are better than others at handling this but how much noise you can live with is a personal thing. Generally, you’ll want to use the lowest ISO setting you can get away with.

The noise that results from using high ISO values can, to a certain extent, be fixed by software – either within your camera itself or using software like Adobe Lightroom. However, this will soften the image slightly so the less this is required, the better. Bear in mind, however, that while ISO problems can be fixed with software, motion blur is far harder to remedy. If it comes down to a choice between dropping your shutter speed so you can use a lower ISO, or going for a faster shutter speed and higher ISO, always go for the faster shutter.

How exposure settings work

Known as the ‘exposure triangle’, the brightness of every image is dictated by a combination of shutter speed, aperture and ISO. Change one of these values and you have to change the others to compensate.

If, for example, you want to shoot car light trails, you’d be looking for a slow shutter speed. This keeps the shutter open for longer so more light would reach the sensor, potentially over-exposing your shot. Therefore, to compensate, you’d want to lower your ISO and/or narrow the aperture, reducing the amount of light that hits the sensor.

In the early days of photography, when lenses came with fixed apertures and focal lengths, it was important to instinctively know which shutter speed would give you a correctly-exposed shot. That gave rise to what’s known as the ‘sunny 16 rule’.  On a clear, sunny day, with an aperture of f/16, your shutter speed will be the inverse of your ISO. That means if you’re shooting at ISO 100 then your shutter speed should be 1/100s.

While handy to know, these days cameras have their own inbuilt light meters and can work out the correct exposure settings perfectly well themselves. That’s where the two partial-automatic modes come into their own. Aperture Priority enables you to decide the exact aperture you want, and leave the camera to work out the corresponding shutter speed. Shutter Priority does the same in situations where it’s the shutter speed that’s critical. Stick to one of these two camera settings and you’ll be ready to go whenever you pick up your camera.

Motion blur

Getting the right exposure setting is one thing, but if you’re shooting handheld you also need to think about motion blur. Shoot too slowly and the shot will pick up your movements as you try to hold the camera steady; this becomes more of a problem the longer lens you use. The general rule of thumb is that the minimum shutter speed should be the inverse of the lens you’re using. So if you’re shooting with a 50mm lens, you can go down to about 1/50s handheld without blur. However, cameras and lenses with image stabilisation allow you to get blur-free shots at even slower speeds, and if you can prop yourself against a stable surface you’ll do even better.

Of course, sometimes you want motion blur. This shot is taken by pressing the trigger then moving the camera so that it follows the bike through the length of the exposure. It takes some practice but works well when you get it right.

To guarantee your shutter speed is always above a certain level, there’s an ISO Auto mode. This enables you to set a minimum shutter speed so that if your shot requires going lower than that, the Auto ISO mode kicks in and raises the ISO a bit so your minimum shutter speed can be maintained. This is particularly useful in dark conditions or when moving around from light to dark, because you can set the aperture you want and leave the camera to worry about the other two corners of the triangle.

Full control

There are a few cases when only manual will do. If you’re shooting a series of images and need them all to be at the identical light level, you’ll want to switch to manual. In this case you wouldn’t want the camera to keep adjusting the shutter speed because every image would look slightly different. If you switch to Auto and make a note of the settings your camera has chosen, then flick to manual and key in those settings, you’ll be in roughly the right place.

Another feature digital cameras offer over smartphones is the ability to take photos in RAW format. Unlike JPEGs, RAW files contain much more information about the scene. It means that areas of the shot that appeared over- or under-exposed may still be retrievable from a RAW file. For this reason, you might choose manual if you’re confident that any overexposed areas can be fixed in the post production. 

If you’re using an off-camera flash, it’s difficult to avoid manual. Since your camera can’t calculate the brightness of the shot before taking it, it’s impossible for it to adjust the exposure settings accordingly. The precise settings you’ll need will depend on how bright your flash is and how far it sits from your subject. Light meter apps can be a big help here but flash photography is an entire subject in itself. If this is something that interests you, Jessops Academy hold courses on Speedlight photography at a branch near you.