BetterPhoto Q&A
Category: New Questions

Photography Question 
Gene Park
 

does 400 ASA = 400 ISO


I've always assumed that a 400 ISO rated fill was the same as the old ASA rating, ie 400.


To love this question, log in above
1/9/2008 2:43:59 PM

 
Christopher A. Walrath
BetterPhoto Member Since: 4/25/2006
  Hi, Gene. In a word, Yes. I have an old Zeiss Ikon Contiva 35mm rangefinder that I use when I don't feel like humping half of a studio into the field and the film speed settings are in ASA, actually ASA20, ASA40, ASA80, ASA160, ASA320 and ASA650. For ISO 400 film I set the dial just past ASA320 but between that and ASA600 and the exposures are spot on. So, for an older camera with ASA settings, the settings for ASA correlate into ISO ratings.


To love this comment, log in above
1/9/2008 4:29:13 PM

 
Gene Park   Thanks, I usually set the ASA number as the same as the ISO on the film cartridge.
I've just recently reactivated my Olympus OM-G and Nikon FTN (found 1.3v batteries)because I feel I take better photos with film rather thand digital.
Gene


To love this comment, log in above
1/9/2008 4:36:58 PM

 
Alan N. Marcus   Hi Gene,

The film speed value assigns a numeric value number to the sensitivity of a photographic material. Methods and tests to establish this value started with Messrs.Hurter and Driffield, two British amateur photographers who together founded the science of Sensitomerty / Densitometry in 1890. At that time, film speed was known as H&D speed. In the 1930ís Kodak Labís Loyd Jones and co-workers refined this science. The American Standards Association adopted the Kodak method in 1960. The International Standards Organization adopted the ASA method and then made refinements. While there are minor differences they are not significant and ISO remains the benchmark method.

Over the years, other methods were developed by light meter makers, General Electric and Weston, whoo independently established film speeds. So too did the European film makers who created a system known as the DIN for Deutsche Industrial Norm. Not to be outdone, the British established BAS using ASA methods. The Russians chimed in with GOST.

Only ISO survived.

Alan Marcus (marginal technical gobbledygook)
Anaheim, CA
ammarcus@earthlink.net


To love this comment, log in above
1/9/2008 4:54:06 PM

 
Gene Park   So, if I understand all of this, if the ISO says 400 I can set my camera for 400 ASA or should I double the ASA rate?
Gene


To love this comment, log in above
1/9/2008 6:29:48 PM

 
Christopher A. Walrath
BetterPhoto Member Since: 4/25/2006
  ISO = (more or less) ASA


To love this comment, log in above
1/9/2008 7:32:49 PM

 
Gene Park   Thank you, I am slow, but I eventually get it.

Gene


To love this comment, log in above
1/9/2008 7:46:25 PM

 
Log in to respond or ask your own question.