The depth of field (DOF) is the distance between the nearest and the furthest objects that are in acceptably sharp focus in an image captured with a camera.
In optics, an aperture is a hole or an opening through which light travels. More specifically, the aperture and focal length of an optical system determine the cone angle of a bundle of rays that comes to a focus in the image plane.
A view camera is a large-format camera in which the lens forms an inverted image on a ground-glass screen directly at the film plane. The image is viewed and then the glass screen is replaced with the film, and thus the film is exposed to exactly the same image as was seen on the screen.
In photography, shutter speed or exposure time is the length of time that the film or digital sensor inside the camera is exposed to light when taking a photograph. The amount of light that reaches the film or image sensor is proportional to the exposure time. 1⁄500 of a second will let half as much light in as 1⁄250.
In photography, bokeh is the aesthetic quality of the blur produced in out-of-focus parts of an image, caused by circles of confusion. Bokeh has also been defined as "the way the lens renders out-of-focus points of light". Differences in lens aberrations and aperture shape cause very different bokeh effects. Some lens designs blur the image in a way that is pleasing to the eye, while others produce distracting or unpleasant blurring. Photographers may deliberately use a shallow focus technique to create images with prominent out-of-focus regions, accentuating their lens's bokeh.
In photography, angle of view (AOV) describes the angular extent of a given scene that is imaged by a camera. It is used interchangeably with the more general term field of view.
A camera lens is an optical lens or assembly of lenses used in conjunction with a camera body and mechanism to make images of objects either on photographic film or on other media capable of storing an image chemically or electronically.
In photography and cinematography, a wide-angle lens refers to a lens whose focal length is substantially smaller than the focal length of a normal lens for a given film plane. This type of lens allows more of the scene to be included in the photograph, which is useful in architectural, interior, and landscape photography where the photographer may not be able to move farther from the scene to photograph it.
Cinematography is the art of motion picture photography.
Macro photography is extreme close-up photography, usually of very small subjects and living organisms like insects, in which the size of the subject in the photograph is greater than life size . By the original definition, a macro photograph is one in which the size of the subject on the negative or image sensor is life size or greater. In some senses, however, it refers to a finished photograph of a subject that is greater than life size.
In digital photography, the crop factor, format factor, or focal length multiplier of an image sensor format is the ratio of the dimensions of a camera's imaging area compared to a reference format; most often, this term is applied to digital cameras, relative to 35 mm film format as a reference. In the case of digital cameras, the imaging device would be a digital image sensor. The most commonly used definition of crop factor is the ratio of a 35 mm frame's diagonal (43.3 mm) to the diagonal of the image sensor in question; that is, . Given the same 3:2 aspect ratio as 35mm's 36 mm × 24 mm area, this is equivalent to the ratio of heights or ratio of widths; the ratio of sensor areas is the square of the crop factor.
A telecentric lens is a special optical lens that has its entrance or exit pupil, or both, at infinity. The size of images produced by a telecentric lens is insensitive to either the distance between an object being imaged and the lens, or the distance between the image plane and the lens, or both, and such an optical property is called telecentricity. Telecentric lenses are used for precision optical two-dimensional measurements, reproduction, and other applications that are sensitive to the image magnification or the angle of incidence of light.
The following are common definitions related to the machine vision field.
Tilt–shift photography is the use of camera movements that change the orientation or position of the lens with respect to the film or image sensor on cameras.
A photographic lens for which the focus is not adjustable is called a fixed-focus lens or sometimes focus-free. The focus is set at the time of lens design, and remains fixed. It is usually set to the hyperfocal distance, so that the depth of field ranges all the way down from half that distance to infinity, which is acceptable for most cameras used for capturing images of humans or objects larger than a meter.
Miniature faking, also known as diorama effect or diorama illusion, is a process in which a photograph of a life-size location or object is made to look like a photograph of a miniature scale model. Blurring parts of the photo simulates the shallow depth of field normally encountered in close-up photography, making the scene seem much smaller than it actually is; the blurring can be done either optically when the photograph is taken, or by digital postprocessing. Many diorama effect photographs are taken from a high angle to simulate the effect of looking down on a miniature. Tilt–shift photography is also associated with miniature faking.
Tilted plane photography is a method of employing focus as a descriptive, narrative or symbolic artistic device. It is distinct from the more simple uses of selective focus which highlight or emphasise a single point in an image, create an atmospheric bokeh, or miniaturise an obliquely-viewed landscape. In this method the photographer is consciously using the camera to focus on several points in the image at once while de-focussing others, thus making conceptual connections between these points.
An ultra wide-angle lens is a lens whose focal length is shorter than that of an average wide-angle lens, providing an even wider view. The term denotes a different range of lenses, relative to the size of the sensor in the camera in question.
In photography, the 35 mm equivalent focal length is a measure that indicates the angle of view of a particular combination of a camera lens and film or sensor size. The term is popular because in the early years of digital photography, most photographers experienced with interchangeable lenses were most familiar with the 35 mm film format.
The design of photographic lenses for use in still or cine cameras is intended to produce a lens that yields the most acceptable rendition of the subject being photographed within a range of constraints that include cost, weight and materials. For many other optical devices such as telescopes, microscopes and theodolites where the visual image is observed but often not recorded the design can often be significantly simpler than is the case in a camera where every image is captured on film or image sensor and can be subject to detailed scrutiny at a later stage. Photographic lenses also include those used in enlargers and projectors.
