Field of view refers to the extent of the scene that is visible through a camera's viewfinder compared to what will actually be captured on the film or sensor. In SLR cameras, the design, size, and position of the mirror, pentaprism, or other optical elements can prevent the viewfinder from showing the entire image area, meaning photographers often see less than 100% of what the camera records. The higher the percentage of viewfinder coverage, the more accurately the photographer can compose and frame the image. Professional cameras typically offer 100% field of view, ensuring precise alignment between what is seen and what is captured.
Understanding field of view is essential for photographers, particularly in professional or critical applications where accurate composition is crucial. Being aware of any discrepancy helps prevent unintended elements from appearing at the edges of the final image, improving both framing accuracy and overall image quality.