Can be characterized in terms of absolute film sensitivity or in terms of reproduced image blacks. Absolute sensitivity is simply a measure of what level of light (exposure) begins to produce the first density signal in the film - this is known as toe speed. The toe speed of a film can also be interpreted by a cinematographer as underexposure latitude or shadow detail. The blackness of a positive image D-max can also be used to define speed. Most cinematographers would describe a film with smokier blacks as slower than a film with blacker blacks given both were exposed similarly. Black level also relates to a cinematographer s perception of shadow detail.kodakcine
A measure of the sensitivity to light of a photographic emulsion. May also refer to the sensitivity setting employed in a digital camera.
An announcement made by either the director of photography or camera operator indicating to the director that the camera is operating at the correct speed. Called just after lock it down, and just before action.
The higher the ISO/ASA number, the more sensitive (faster) and usually the grainier the film. See: Gain, for the video equivalent of sensitivity and Background Noise as the parallel to grain.
The largest Stop (smallest number!) a lens can provide. Tip: High-speed lenses are great for low-level illumination but limited in terms of Depth of Field when wide open.
186,000 miles per second.