This is a key part of the optical viewfinder system of a digital SLR. It’s a five-sided prism inside a housing on top of the camera that reflects the image captured by the lens and formed on the camera’s focusing screen so that it’s the right way up and the right way round for viewing […]
Viewfinders
While most cameras now let you compose your shots using an LCD screen on the back, there are lots of times when a regular viewfinder is still preferable. For many people it's more natural to put your eye to a viewfinder eyepiece than it is to hold the camera at arm's length. Viewfinders are also more useful in bright light, when glare often makes it hard to see what's being displayed on an LCD screen. Viewfinders come in different types. Some older cameras have 'direct vision' viewfinders, digital SLRs have optical through-the-lens viewfinders while mirrorless cameras use electronic viewfinders.
Photo by Felix Russell-Saw on Unsplash
Viewfinder grid
These are an option on both DSLRs and in electronic viewfinders. You can use the grid to make sure horizons are level and buildings are vertical – some grids confirm to the ‘rule of thirds’ to help you get a satisfying composition.
Viewfinder coverage
The percentage of the scene shown by the viewfinder. In better DSLRs you see 100% of the scene that will be captured, but in cheaper models it might only be 95-97%. That small difference can lead to objects showing at the edge of the frame that you hadn’t realised were there.
Rangefinder
An older camera designed still used by celebrated German manufacturer Leica. The ‘rangefinder’ is used for focusing – as you turn the focus ring on the lens, a small mirror in the top of the camera rotates to line up a ‘ghost’ image with the main image in the viewfinder. When this ghost image lines […]
Optical viewfinder
The viewfinder in a digital SLR is optical because it’s created by an image formed by the lens on a glass ‘focussing screen’. The direct vision viewfinders on some compact cameras are optical because you’re seeing the world through a set of lenses and not via a digital display.
OLED display
OLED stands for ‘organic light emitting diode’. It’s a more advanced display tech than regular LCDs with wider viewing angles, faster response, better brightness and reduced power consumption. The OLED electronic viewfinder is a selling point in the Fujifilm X-T1, for example.
Eyepiece shutter
A tiny blind in the viewfinder eyepiece that stops light entering and upsetting the exposure (normally the eyepiece is covered by your eye). It can be useful for long exposures or other shots where you’ve stepped away from the camera. Some cameras come with a small viewfinder cap fixed to the shoulder strap.
Electronic viewfinder
Essentially, this is a tiny LCD display seen through a magnifying eyepiece. They’re used on some bridge cameras and high-end compact cameras, and on many mirrorless cameras. They replace the optical viewing system you get with a DSLR.
Dioptre adjustment
A small knob or lever next to the viewfinder which you use to adjust the focus of the eyepiece to match your own vision. The information in the viewfinder should appear sharp without you having to strain to bring it into focus.