Archived posting to the Leica Users Group, 1999/07/12
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Actually, it was a change of the way ASA rating was established. Between 1941 and 1960, the ASA value represented more or less (I lack english vocabulary) the contrast of the film between the point it was recording something and a medium lumination. From 1960, the norm was simplified to represent some fixed (supposely representative) densities when a given processing was applied. The ISO norm is more or less a mix of the two methods. In a word, ISO norm represents the contrast of the film and the second ASA norm its density. All the best. - -- Jean-Claude Berger (jcberger@jcberger.com) Systems and RDBMS consultant (MCSE) Lyon, France http://www.jcberger.com - -----Original Message----- From: owner-leica-users@mejac.palo-alto.ca.us [mailto:owner-leica-users@mejac.palo-alto.ca.us]On Behalf Of A.H.SCHMIDT Sent: Monday 12 July 1999 13:32 To: leica-users@mejac.palo-alto.ca.us Subject: Re: [Leica] Leica Users digest V10 #15 Doug Richardson wrote: Snip: Doug, There was a change in the ASA figures sometimes , I think , after the second world war. The film manufacturers started to get a bit more "optimistic" in the film speeds. What was before 100ASA turned in to 125ASA. Maybe some of the LUGers know a bit more about it. It saves me looking it up.