viewfinders

A viewfinder is a device on a camera that allows the photographer to see the scene, frame the shot, and often focus, without relying on the final image on the sensor. Viewfinders come in several implementations, including optical viewfinders, rangefinder viewfinders, and electronic viewfinders, each with distinct advantages and limitations.

Optical viewfinders provide a direct optical path from the scene to the eye. In single-lens reflex (SLR) cameras, an internal mirror and a pentaprism or pentamirror transmit the image from the lens to the eye, offering bright, real-time composition without battery power. However, the image can be dim in low light, and close subjects may suffer parallax error when the viewfinder is not perfectly aligned with the lens.

Rangefinder viewfinders use a separate window to frame the scene and rely on a focusing mechanism that aligns two images or uses triangulation to determine focus. They are compact and quiet and are common in older or specialized cameras, but their framing may diverge from the exact lens view at close distances, known as parallax.

Electronic viewfinders display a live image from the camera’s sensor on an LCD or OLED panel. Common in mirrorless cameras, EVFs can preview exposure, white balance, and depth of field, and often include overlays, histograms, and focus peaking. Drawbacks include latency, potential resolution limits, and higher power consumption.

Key specifications include magnification and eye relief for optical viewfinders, and resolution, refresh rate, and latency for electronic viewfinders. The choice of viewfinder affects framing accuracy, focusing speed, and overall shooting experience.