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Fly back period
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The time taken for a signal to move from the end of a field, frame or line to the start of the next field frame or line. also called the retrace period.
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Focal length, английский
- The distance between the optical centre of a lens and the focal point.
- Положение главной задней плоскости зависит от типа объектива: у нормальных объективов она находится недалеко от диафрагмы, у телеобъективов она расположена перед линзами, а у объективов с удлинённым главным отрезком - сзади них. поэтому главное фокусное р
- Imaging device size
- The distance between the center of a lens, or its secondary principal point and the imaging sensor. lower lengths give a greater field of view and less magnification. longer lengths give a narrower field of view and greater magnification. the table below gives an approximate value for the angle of the field of view for lenses of various focal lengths and also considering the size of the imaging device (ccd). most cctv cameras have one of the 3 sizes of imaging devices listed below, 1/4", 1/3" or 1/2". almost all of cctv camera pros cameras have 1/3" sony ccd imaging devices.
- Of a lens, the distance from the focal point to the principal point of the lens.
- The distance from the center of the lens to a plane at which point a sharp image of an object viewed at an infinite position. the focal length determines the size of the image and angle of field of view seen by the camera through the lens. this is the center of the lens to the image pickup device.
- The distance between the optical center of a lens and the principal convergent
- The distance from the center of the lens to a plane at which point a sharp image of an object viewed at an infinite position. the focal length determines the size of the image and angle of fov seen by the camera through the lens. this is the center of the lens to the image pickup device.
- Distance between the optical center of a lens and the image focal point. fixes the magnification and the angle of view of a lens. vari-focal and zoom lenses have a variable focal length.
- A lens` angle of view, most commonly indicated as wide angle, normal or telephoto. usually compared to a 35mm camera`s lenses as in the camera has a wide angle lens equivalent to a 38mm lens on a 35mm camera. see also zoom lens
- The distance between the optical center of a lens and the principal convergent focus point.
- Distance between the center of a lens and the point on the optical axis to which parallel rays of light are converged by the laser.
- A measure of how strongly an optical system focuses or defocuses light
- The distance from the lens to the film plane or sensor that focuses light at infinity. the length, expressed in millimeters, is more useful as an indication of the angle of view of a particular lens. a shorter focal length lens, such as a 28mm, offers a wider angle of view than a longer one, such as 100mm.
- A lens’ angle of view. such as wide angle, standard or telephoto.
- The distance from the back vertex of a lens to its focal point.
- The distance between the object-glass and the eye-piece of a telescope.
- The distance between the camera’s lens and the image plane. focus (n)
- The distance from the lens to the image point when the object is at a definite distance from the lens (this is also the distance to the focal point)
Fixed lens, английский
- A lens with a pre-determined fixed focal length. normally has a focusing control and a choice of iris functions. available in a range of sizes to suit different applications.
- A fixed focal lens does not allow the fov to be adjusted; the camera`s focal length is permanently set.
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