Viewfinders can play an important part in image composition. They allow you to arrange and focus the perfect shot, without having to rely on an LCD screen that you might struggle to see in bright sunlight.
Although some cameras (mainly compact models) lack a viewfinder, most DSLR and mirrorless digital cameras now have one.
A viewfinder is the part of the camera you hold up to your eye and look through to preview an image before you snap.
There are two types:
As well as showing an image preview, both types can overlay key details about the settings being used for your shot, usually tucked around the margins of the view so they don't unduly obstruct the image.
For most photographers, the differences between an optical and an electronic viewfinder are subtle. Because of this, we advise buyers to judge a camera on all of its merits and not just its viewfinder.
On the back of pretty much all modern digital cameras you'll also find a small screen, or monitor, that you can use to preview an image. However, this requires you to extend your arms and hold your camera well away from your eyes.
As well as reducing the stability of the shot and potentially feeling less natural, large monitors are prone to looking dim in sunlight and reflecting glare. An image also looks much bigger and clearer when viewed at close proximity, as seen through a viewfinder.
An OVF uses a mirror and a prism to bounce light through the lens and towards your eye. This means you can see what's in front of your camera exactly as you'd see it if you were looking directly at it, with none of the slight time lag that you sometimes find with electronic viewfinders (see below).
What they won't necessarily show you is what the final image will look like, for example if you're using the camera's auto settings and it makes adjustments to take account of low light levels.
An EVF is essentially a tiny screen; it replicates what you'd see on the main monitor. Rather than viewing the scene through a series of mirrors, you see a digital capture of the world through your camera's sensor. This means that what you see is very close to what the camera will ultimately capture.
Most electronic viewfinders use LCD screens, but the most premium are starting to used OLED displays for both their viewfinders and monitors.
It's largely a matter of personal preference, and how advanced your photography is.
Generally, high-end DSLRs and mirrorless cameras have a viewfinder by default, so there's no need to weigh up the pros and cons.
Meanwhile, if you're a smartphone snapper, you'll have no choice but to rely on your screen preview. But smartphones are best for casual photography in the first place, so the lack of a viewfinder is less likely to be an issue.
If you're after a compact camera, though, you'll have a decision to make – just under half of the compact cameras we've tested have a viewfinder.
Ultimately, a viewfinder is a tool to help you compose the perfect shot and, like any tool, it's only valuable if you use it. If you find it easier to compose your shot using a larger LCD screen, then a viewfinder might simply be taking up space on your camera.
That said, viewfinders – whether optical or electronic – have a number of advantages in terms of reducing glare and improving stability, and can be a good feature to have, even if you don't use the viewfinder for every shot.