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The ASA scale is a linear scale, that is, a film denoted as having a film speed of 200 ASA is twice as fast as a film with 100 ASA. The ASA standard underwent a major revision in 1960 with ASA PH2.5-1960, when the method to determine film speed was refined and previously applied safety factors against under-exposure were abandoned, effectively ...
The sensitivity of a (digital or film) imaging system is typically described in the terms of the signal level that yields a threshold level of SNR. Industry standards define sensitivity in terms of the ISO film speed equivalent, using SNR thresholds (at average scene luminance) of 40:1 for "excellent" image quality and 10:1 for "acceptable ...
In photography, reciprocity refers to the relationship whereby the total light energy – proportional to the total exposure, the product of the light intensity and exposure time, controlled by aperture and shutter speed, respectively – determines the effect of the light on the film. That is, an increase of brightness by a certain factor is ...
The implied value (1/3.125) for the speed scaling constant given in the Exif 2.2 specification ("Exif 2.2"; JEITA 2002) differs slightly from the APEX value of / (0.2973); with the Exif value, an ISO arithmetic film speed of 100 corresponds exactly to a speed value [3] of 5.
A roll of Cinestill 135 color film showing checkboxes that can be used to remember the EI for push-processing (expressed in stops relative to the box speed of ISO 800/30°). When a film's effective sensitivity has been varied, the resulting sensitivity is called the exposure index ; the film's speed remains at the manufacturer's indication.
The Zone System is a photographic technique for determining optimal film exposure and development, formulated by Ansel Adams and Fred Archer. [1] Adams described the Zone System as "[...] not an invention of mine; it is a codification of the principles of sensitometry, worked out by Fred Archer and myself at the Art Center School in Los Angeles, around 1939–40."
Selecting any shutter speed faster than the camera's rated X‑sync speed, which is often between 1 / 60 th and 1 / 200 th of a second (from as long as 16.7 milliseconds to as little as 5.0 milliseconds) causes the shutter curtain to begin wiping closed across the film or sensor before the flash has extinguished. When this happens, an ...
The telerecording film chain can be arranged to produce a direct negative-image film recording, a direct positive-image film recording, or a positive print can be made from the negative. In the first two cases we have the following four units in which local gamma or effective image contrast may be adjusted: The recording channel amplifier.