Altering the settings on focal length, lens angle, zoom ratio, aperture or depth of field will have a significant influence on the perspective and the depiction of space and composition when setting up a shot. It is a fallacy to believe that the camera will truthfully record whatever is in shot whenever you put your eye to the viewfinder and press to record. If you are unaware of how the choice of focal length, etc., will affect the chosen image then this important creative decision will be left to chance and accident.
Prime lens or zoom?
Before the introduction of colour
television, video cameras usually had four, individually turret-mounted prime lenses (a lens with a fixed
focal length) on the front of the camera. By rotating the turret, the correct lens for a specific focal length would be chosen for a shot. Selecting a prime lens to match the needs of a shot is still common film practice. For technical reasons, such as faster working methods and the option to zoom on shot to capture close-ups without adjusting the camera, meant the wide majority of colour video cameras were fitted with a zoom lens. With the ability to change the lens angle quickly and easily, it can be easy to forget what focal length is being used which could compromise the space or perspective of the shot so be wary.
Image size
With CCD (charged couple devices) coming in different sizes (2/3 inch, 1/2 inch, etc.), the variation in flange-back distance the mechanical
connection between lens and camera, and the variation in cable connections with
the camera, it is often impossible to interchange lenses between different makes
or models of cameras. The image formed by the lens on the face of the CCDs is
called the image size of the lens. This must match the size of the camera sensor.
Lenses designed for different sized formats (pick-up sensor dimension) may not
be interchangeable. The image size produced by the lens may be much smaller
than the pick-up sensor and
probably the back focus (flange _‘back) will not have sufficient adjustment. A
common lens on a broadcast video camera is a 14 x 8.5 f1.7 zoom with a
minimum object distance of 0.8 m or below.
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