craig rainbolt Posted June 17, 2005 Share Posted June 17, 2005 How can ISO be compared to the film ASA? Link to comment Share on other sites More sharing options...
ted_marcus1 Posted June 17, 2005 Share Posted June 17, 2005 Multiply ASA by 1.00 to get ISO. Or multiply ISO by 1.00 to get ASA. All seriousness aside, the International Organization for Standardization (ISO) adopted both the American Standards Association (ASA) and the German DIN standard as their international standard for film speed. Technically an ISO film speed is supposed to state both, but the DIN portion seems to be fading into obscurity. The remaining ISO speed number is thus identical to the former ASA. Link to comment Share on other sites More sharing options...
robin_sibson1 Posted June 18, 2005 Share Posted June 18, 2005 If I remember correctly, at some point the American Standards Association (ASA) changed its name to the United States of America Standards Institute (USASI). If it can't standardise its own name, no wonder ISO had to step in! Link to comment Share on other sites More sharing options...
jcuknz Posted June 18, 2005 Share Posted June 18, 2005 You simply change the letters and leave the numbers as is ... :-) Link to comment Share on other sites More sharing options...
joseph_wisniewski Posted June 18, 2005 Share Posted June 18, 2005 Robin, - The ISO waffled for decades between ISO and OSI (organization standards internationalle). The switch of film speed from ASA to ISO really had to do with the rest of the world finally getting into photography in the 70's. Link to comment Share on other sites More sharing options...
digitmstr Posted June 18, 2005 Share Posted June 18, 2005 Lest we forget DIN Link to comment Share on other sites More sharing options...
jcuknz Posted June 18, 2005 Share Posted June 18, 2005 Nor forget Weston or GE .... which way is which to ASA .... such a long time ago. Link to comment Share on other sites More sharing options...
kelly_flanigan1 Posted June 18, 2005 Share Posted June 18, 2005 To convert asa/iso to din:<BR><BR>Take the base 10 log of the asa<BR><BR>multiply by 10<BR><BR>add 1<BR><BR>Thus asa 100 is din 21; asa 1000 is din 31<BR><BR>an increase of 3 din is double the asa; ie the log of 2 is about 0.30103<BR><BR>this formula was used 40 years ago; and fits most all current films today; even if the formal specs are a tad different.<BR><BR>Thus the asa 100 is din 21; the base log of 100 is 2; multiply by 10 and get 20; add one and get 21. Thus asa 200 is 24; asa 400 is 27; adding 3 din for each 2x increase.<BR><BR>Just a good slide rule formula used from the 1960's; also in some spie books and optical engineering and kodak literature that is scientific; non amateur. Link to comment Share on other sites More sharing options...
awindsor Posted June 19, 2005 Share Posted June 19, 2005 To be strictly correct 100 is the ASA speed, 21 is the DIN speed, and the ISO is 100/21. Compromise is a wonderful thing. Link to comment Share on other sites More sharing options...
kelly_flanigan1 Posted June 19, 2005 Share Posted June 19, 2005 Actually "To be strictly correct" the ISO is 100; the DIN speed is 21. <BR><BR>An ISO 100/21 is totally wrong. <BR><BR>There should be a little superscript "degree" mark after the "21"; to tag it as DIN. <BR><BR>ie ISO 100/21� is what the federal trade commission use to require; not a sloppy ISO 100/21 marking. <BR><BR>I am not sure if the superscript degree mark will show up in folks browsers; it is after the 21.<BR><BR> iso100/21� Link to comment Share on other sites More sharing options...
kelly_flanigan1 Posted June 19, 2005 Share Posted June 19, 2005 It is interesting that the superscript degree appears correct in the preview before posting; but comes up as a question mark after posting; using mozzila firefox iso. when a preview is done in "plain text" the supercript does appear as a question mark before posting 100/21? Link to comment Share on other sites More sharing options...
joseph_wisniewski Posted June 19, 2005 Share Posted June 19, 2005 Unfortunatly, you can't do a degree symbol in plain text, it's not HTML safe. The only way to get one is to use HTLM, where it's amphersand deg, like this: 21° Link to comment Share on other sites More sharing options...
kelly_flanigan1 Posted June 19, 2005 Share Posted June 19, 2005 The only way to get one is to use HTLM, where it's amphersand deg, like this: 21° test with plain text Link to comment Share on other sites More sharing options...
kelly_flanigan1 Posted June 19, 2005 Share Posted June 19, 2005 The only way to get one is to use HTLM, where it's amphersand deg, like this: 21° test with HTML Link to comment Share on other sites More sharing options...
kelly_flanigan1 Posted June 19, 2005 Share Posted June 19, 2005 <h3>ISO 100/21°</h3><BR><BR>@FIN!<BR><BR>Thanks!!!!<BR><BR> Link to comment Share on other sites More sharing options...
kelly_flanigan1 Posted June 19, 2005 Share Posted June 19, 2005 Joseph; in my way earlier posts I used a 21° pasted in from another link; and it it was posted in HTML; and appeared as a 21° in the preview using "the above test is HTML" selected; and a 21? after posting. Link to comment Share on other sites More sharing options...
kelly_flanigan1 Posted June 19, 2005 Share Posted June 19, 2005 Learning some more HTML things and weirdnesses is a wonderful thing too. Link to comment Share on other sites More sharing options...
digitmstr Posted June 20, 2005 Share Posted June 20, 2005 Ah! 21° Link to comment Share on other sites More sharing options...
joseph_wisniewski Posted June 22, 2005 Share Posted June 22, 2005 Oh my God, I've created a monster. Make that two monsters. ;) Link to comment Share on other sites More sharing options...
awindsor Posted June 23, 2005 Share Posted June 23, 2005 <i>The only way to get one is to use HTLM, where it's amphersand deg</i><P> Mea culpa, Kelly. Interestingly you can write ° in an HTML post provided you know to write & for the &. <P> What's HTLM ? Link to comment Share on other sites More sharing options...
joseph_wisniewski Posted June 27, 2005 Share Posted June 27, 2005 Alistair, HTLM stands for Hypertext Larkup Manguage. Gosh, don't you know anything about the Welrd Vide Wheb? Link to comment Share on other sites More sharing options...
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