A viewfinder is the little display unit on top of a DSLR or mirrorless camera. It is an essential component of a camera because it is the “window” through which a photographer looks to compose the photographs. Not all cameras have it, in that case, the photographer will use the rear LCD screen.
Whatever you see through the viewfinder is the exact image you will capture. Furthermore, it also lets you focus more accurately when shooting. When you use the viewfinder, you will bring the camera close to your eye, allowing for a more accurate and stable shoot.
When using the LCD screen instead, you’ll keep the camera distant from you. As a result, you risk missing focus or obtaining a blurred photo due to camera shaking.
The viewfinder is a tiny rectangular screen built into almost all modern DSLR and mirrorless cameras. It’s a useful tool, mainly when shooting action photography. With fast-moving subjects, it helps the photographer frame images accurately.
The viewfinder displays significant camera settings. It shows focus points, the light meter, exposure information, shutter speed, aperture, and ISO, among other settings.
Diopter: shooters using correction glasses can use the diopter to adjust the focus and getting a sharp image on the small screen.
You can watch this video if you want to learn how to adjust the diopter.
When the light passes through the lens a mirror bounces it to a prism that directs it to the viewfinder. This system is the pentaprism. Full-frame and professional DSLRs feature a pentaprism, while APS-C cameras have a pentamirror. The pentamirror as the name suggests uses a mirror to reflect the light to the viewfinder. They are less bright than pentaprisms.
Curiosity: pentaprisms are probably the reason why single lens reflex (SLR) cameras have been a success. Older systems could have the image turned the other way around or flipped.
In old rangefinder cameras, the viewfinder and the lens were separate from each other. The downside was that it created a parallax effect with subjects too close to the camera.
Today’s cameras look through the lens. They have optical or electronic viewfinders.
- The Optical Viewfinder (OVF) is built-in in DSLR cameras. The light passes through the lens (TTL), hits a mirror that reflects it into the viewfinder via a pentaprism. The picture you see through this viewfinder tends to be sharp and bright since it’s the same image seen by the lens.
- In the Electronic or Digital Viewfinder (EVF), the light passes through the lens. Before hitting the sensor, it’s processed and displayed on the viewfinder LCD as a digital image. The EVF is in mirrorless cameras and consumes battery power, unlike optical viewfinders.
Both optical and electronic viewfinders have their sets of advantages and downsides. When looking through an EVF, you’ll see much more information. Thanks to the brightness of the electronic viewfinder, you can see even in dark conditions.
Holding the camera up to the eye has certain advantages. It’s useful to see info such as the histogram, focus peaking, and image playback. Access to these settings while looking through the viewfinder makes shooting easier.
For this reason, mirrorless cameras have made DSLRs look old in this regard. But on the other side, DSLR cameras benefit from a real live view with no time delay. Besides, on a DSLR, the battery lasts longer thanks also to the optical viewfinder not consuming power.
Now that you know how things works internally, you will make a more informed decision when buying your next camera.
Stefano Caioni is a photographer from Sydney, Australia. Founder and editor of Pixinfocus, his passion for photography helps him explore new places and live new adventures. Thanks to photography he reconnected with the outdoors and was able to travel the world and take photos of some of the most beautiful places on Earth.