Here are some helpful definitions for lenses, optics, and so much more. Refer to these terms for all the need-to-know information about optics.
- Aberration: Any defect in image quality resulting from a failure or deficiency of equipment or processes. Examples include distortion, coma, or chromatic focal shift.
- Aperture: The hole in a lens through which light is able to pass. Aperture size, measured by F-number, affects the level of brightness and sharpness possible in a photo.
- Bandpass Filter: An optical filter that restricts or isolates certain wavelengths within a specified range.
- Bandwidth: The width of a frequency that can be transmitted by an optical device or element.
- Bezel: The border or frame around a display screen, such as an LED screen. Provides structural support and protection to an image display system.
- C-mount: A standard camera mount configuration, providing a 17.526 flange focal distance (FFD). Commonly found on a movie camera, machine vision camera, and microscope phototubes.
- Charge-Coupled Device (CCD): A sensitive photon detector that uses and stores pixels (highly light-sensitive areas) to create an image.
- Collimation: To make two or more diverging beams of light run parallel to one another.
- Complementary Metal Oxide Semiconductor (CMOS): A semiconductor image sensor that is able to amplify pixels individually, rather than in clusters. This system allows for much faster and more direct image access than CCD semiconductors.
- Depth of Field: The distance or range in which an object can be clearly focused by a lens or imaging device. A shallow depth of field puts a heavy focus on nearby, foreground objects, such as in portrait photography. A deep depth of field allows for greater detail over a wider scope, such as in landscape photography.
- Depth of Focus: The distance behind a lens at which an object is considered to be in focus. Differs from Depth of Field (DOF) in that DOF measures the optical range in which objects are focused. Depth of focus, meanwhile, refers to the space between the lens and the imaging device (camera).
- Diopter: Unit of measurement which measures the magnifying or refractive power of a lens. Equal to 1 m divided by the focal length of the lens.
- Distortion: An optical aberration in which lines that are straight in reality, appear to bend outward (barrel distortion) or inward (pincushion) from the center of an image.
- f/No: F-number. The unit of measurement used to determine the speed at which a lens can capture light. F-number is reciprocally linked to the aperture of a lens. A higher aperture means a lower F-number, and vice versa.
- Filter: A component that can be placed over or in front of a lens to restrict certain wavelengths from passing through. Thus, it blocks, absorbs, or reflects certain types of light.
- Fixed Focal Length: A lens with a fixed focusing distance that cannot be adjusted or refocused for other distances. One of the most common types of photographic lenses.
- Focal Length and Effective Focal Length: An optical property of the lens measuring the optical distance from its center to the camera sensor, measured in millimeters. Effective Focal Length is used to determine how much of a scene is able to be captured by a lens.
- Laser: Light Amplification by Stimulated Emission of Radiation. A highly powerful, highly concentrated beam of light of consistent frequency, color, and direction.
- Lens Assembly: Configuration of a lens along with other optical components, such as lens mounts and filters.
- Lens Format: The shape and size of a particular lens.
- Lens Mount: A device or structure which is used to support or configure the lens and any other optical components in use.
- Magnification: Ratio of the size of an image to the actual object; enlargement of an object in the imaging process by an optical device.
- Optics: The scientific field dealing with the appearance, transmission, and behavior of light and other types of radiation. The implementation of optical systems for the purpose of studying optics.
- Polarization: The process of affecting light waves so that all waves are made to vibrate on a single plane. By contrast, non-polarized light waves will move in all directions along multiple divergent planes.
- Refraction: A change in the direction of a ray of light when passing through two materials or surfaces.
- S-mount: A common type of lens mount that uses a 0.5mm pitch and has no specified flange focal distance. Commonly used in closed-circuit television cameras, among other optical devices.
- Ultraviolet (UV) Spectrum: The range of the electromagnetic spectrum relating to ultraviolet light. Ultraviolet radiation has much shorter wavelengths than most visible colors, and is thus often invisible to the naked eye.
- Visible Spectrum: The range of the electromagnetic spectrum that is visible to the human eye. Wavelengths between 380 to 700 nanometers.
- Wavelength: The length of a wave measured from any one point on the wave to the next corresponding wave. Wavelength is typically measured from the crest, or tip, of one wave to the next. Only wavelengths within a limited range (the visible spectrum) are visible to the human eye without technological assistance.
- Working Distance (WD): The distance between the front of the lens and the object it is focused on.
- Zoom: Changing the magnification of a lens without changing the working distance between the lens and its object of focus.