What is ASA ?
Parnian
Darrell A. Larose
Parnian (far2) writes:
> What is ASA ?
>
The old American Standards Association, generally was used as a film speed
system until the more recent ISO (International Standards Organization)
film speeds were introduced. ISO actually combined both the ASA rating
with the DIN (German Industrial Standards) into a single rating. So the
format is: ISO 100/21
old ASA===>^^^ ^^ <===old DIN
Nothing all that mysterious.
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Darrell A. Larose | ad...@freenet.carleton.ca
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maohai huang
: What is ASA ?
American Sailing Association
- mh
Martin Tai
-> What is ASA ?
ASA stands for American Standards Association
Kodak film uses both ASA film speed and DIN speed
For instance Kodachrome 64 is ASA scale, the equivalent
DIN scale = 19.
ASA 100 = DIN 21
ASA 200 = DIN 24
ASA 400 = DIN 27
ASA 800 = DIN 30
ASA 1600 = DIN 33
....................
SHAVE THE MOOSE
a Side, and another Angle. Useful for computing depth of field. 8^)
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Jon Louch
sensitivity to light. The higher the number, the more sensitive the film.
The standard is now ISO.
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Jon Louch
George Lathan Jr.
>What is ASA ?
American Sailing Association NOT!! (At least not in this group)
It stands for American Standards Association
It is a standard industry wide guide for stating the speed of a film
or the sensitivity of film to light. The numbers start at about 25 and
go as high as 3200 for most normal films. The higher the number the
more sensitive the film meaning it needs less light to get a good
exposure or in some cases you can use a faster shutter speed and a
smaller aperture.
BTW ; ISO is the same thing :)
Gord Jeoffroy
It stands for acetlysalicylic acid -- aspirin, to the layman -- and is
something that many photographers are addicted to <grin>.
Actually, is stands for American Standards Association and is used in
rating the "speed" or light sensitivity of film. These days it's ISO
(International Standards Organization) rather than ASA, but the numbers are
essentially the same.
I don't know what the baseline is (i.e., how sensitive ISO 100 film is) but
all you really need to know is that doubling or halving the film speed
means doubling or halving its light sensitivity. In other words, ISO 800
film is twice as sensitive as ISO 400 film, so it needs only half as much
light to make an equivalent exposure.
Clear as mud?
--Gord
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Ron Irvine
ASA 25 1/25 sec. at f16
ASA 100 1/100 sec. at f16
ASA 400 1/400 sec. at f16
Decrease exposure for sand/snow. Increase for cloud/overcast, ...
Patrick M Chase
I always increase exposure for snow scenes so I don't wind up with gray
snow drifts.
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Jacques-Bertrand Pichette
: Parnian <far2> wrote:
: >What is ASA ?
: American Sailing Association NOT!! (At least not in this group)
: BTW ; ISO is the same thing :)
Does ISO stand for "International Sailing Organisation" ? ;-)
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TOM OATES
> What is ASA ?
It stands for American Standards Association. Along with the old
"DIN" rating, it used to be used to indicate the sensitivity (ie speed)
of photographic films. ASA film ratings have been superseded by ISO
(International Standards Organisation) ratings. However, you needn't
concern yourself with details. Put simply, when it comes to films:-
ISO = ASA (the two photo standards are identical)
Some older cameras have the film setting meter marked in ASA units.
So, when you fit (for example) a 200 ISO film in your old (pre-ISO)
camera, just set its meter to 200 ASA and the camera will be perfectly
happy.
- Tom Oates
Michael Ege
Indeed, but does anyone publish a DIN - ASA (ISO) conversion table?
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> ASA is 1 / the shutter speed for a nominal sunlit landscape at f16.
>
> ASA 25 1/25 sec. at f16
> ASA 100 1/100 sec. at f16
> ASA 400 1/400 sec. at f16
>
> Decrease exposure for sand/snow. Increase for cloud/overcast, ...
I think ASA means, American Standards Association. It designates the film
speed just as ISO does. ISO means International Standards Organization.
Foreign countries wanted an international standard instead of an American
standard, so they changed it from ASA to ISO. The higher the number, the
faster the film speed.
-Bob