50mm

50 millimeters (50 mm) is a metric length used to measure distance, width, height, or thickness. In everyday terms, 50 mm is about 2 inches. It is widely recognized in photography as a focal length for lenses and as a common standard unit in optics.

In photography, a 50 mm lens refers to a lens with a focal length of 50 mm. On a full-frame camera, it provides a field of view that is often described as natural or close to human vision, making it a versatile, general‑purpose lens. A 50 mm prime is known for producing moderate perspective, pleasing skin tones in portraits, and relatively shallow depth of field when used at wide apertures. Common variants include apertures such as f/1.4, f/1.8, and f/2.0, which are valued for low‑light performance and subject isolation.

On camera bodies with smaller sensors, such as APS-C or Micro Four Thirds, the same 50 mm lens yields a narrower field of view. This is often described using an effective focal length, which is the real focal length multiplied by the sensor’s crop factor (typically around 1.5x for APS-C or 2x for Micro Four Thirds). As a result, a 50 mm lens on these cameras behaves more like a short telephoto lens in terms of magnification and framing.

Historically, the 50 mm focal length has been central to the idea of a “normal” lens for 35 mm photography, earning nicknames like “nifty fifty.” It is widely available across brands and mounts, and remains a popular choice for photographers seeking a lightweight, affordable, and unobtrusive lens option.