What is ISO or ASA - Camera/Film Sensitivity AKA Filmspeed


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Jul 11, 2006
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#1
This article is about ISO/ASA ratings and how they effect the pictures you take.

A lot of people seemed confused about this..

ISO or ASA in the most basic terms is the speed with which your film or digital camera responds to light, so the higher the ISO/ASA rating the more sensitive the film or CCD/CMOS sensor is to light.

Because of the confusion I've written an extended article about this:

What is ISO or ASA - Camera/Film Sensitivity AKA Filmspeed

The second in my series of basics articles after the one about Aperture or f-stops/f number & Depth of Field, hope someone finds it useful!
 

Oct 31, 2006
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Singapore Central
#2
Since you are writing an article on the sensitivity of your camera sensor (digital) or your film (analogue), you may want to make it more thorough by also touching briefly on DIN. When the world modernized and was forced to adopt a standard sometime back, the ISO adopted the American standard, i.e. ASA and from then onwards, the two are synonymous. Before then, DIN which was the German standard was also widely used. In those days, films that we bought carried both the ASA and DIN rating. For those who care to know, DIN 21 is equivalent to ISO 100. While the ISO number doubles for a sensor or film that is twice as sensitive to light, the DIN number only increases by 3. Therefore ISO 200 is DIN 24 and ISO 50 is DIN 18.

DIN is of course no longer in use. Feeling nolstagic? This brings me fond memories of the Seagul twin lens reflex and the Rollexflex cameras I had used in the past. I didn't own them but merely borrowed them.
 

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