Archived posting to the Leica Users Group, 2006/12/08
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]On Dec 8, 2006, at 4:32 PM, Eric Korenman wrote: > TCN does best at ISO 320. > It gets way too thin at ISO 800. > just 2 cents from shooting hundreds of rolls of the stuff. so far my experience bears this out...BW400, thin at 800....Steve > > Eric > > On 12/8/06, Walt Johnson <walt@waltjohnson.com> wrote: >> >> Steve >> >> It sounds as if you're going to underexpose by a stop. What result >> are >> you looking for? >> >> Walt >> >> Steve Barbour wrote: >> >> > Walt and others... have you shot C41bw 400, at 800 with normal >> > development? Results? >> > >> > I see this now as advantageous, have never done it, but I plan to >> > try.... >> > >> > thankjs, Steve >> > >> > >> > On Dec 8, 2006, at 6:41 AM, Walt Johnson wrote: >> > >> >> I think I'll start shooting all my Tri-X at 666 ISO. BTW has >> anyone >> >> noticed the change (years ago) from ASA to ISO appears useless? >> >> >> >> Henning Wulff wrote: >> >> >> >>>> Doesn't it have something to do with logging rhythms. in .3 >> >>>> increments? >> >>>> >> >>>> Henning Wulff wrote: >> >>>> >> >>>>> At 10:29 PM +0100 12/6/06, Philippe Orlent wrote: >> >>>>> >> >>>>>> I was just remembering my ISO scale on the back of my MP: >> >>>>>> 50-100-200-400-800- etc. >> >>>>>> >> >>>>>> But the zones in between are divided in 3 parts. >> >>>>>> >> >>>>>> So between 50-100: 50/3=16,7 >> >>>>>> Between: 100-200: 100/3=33,33, which would put 160 at 100 >> and 2/3ds >> >>>>>> Two full stops under brings us at >> >>>>>> 400 and 2/3ds >> >>>>>> Which is 400 + (800-400)x2/3= 666,7 >> >>>>>> >> >>>>>> I may be wrong, but it looks like Leica logics to me. >> >>>>>> :-) >> >>>>>> Philippe >> >>>>>> >> >>>>> >> >>>>> ISO is not continuous. It's only defined for the discrete >> >>>>> progression (from 100 to 3200) for 100, 125, 160, 200, 250, >> 320, >> >>>>> 400, 500, 640, 800, 1000, 1250, 1600, 2000, 2500, 3200. >> >>>>> >> >>>>> No numbers in between, ie, there is not 'ISO 300' or 'ISO 666'. >> >>>>> >> >>> >> >>> ISO combines the old ASA and DIN scales, and makes the >> measurement >> >>> methods and ratings equivalent. DIN was logarithmic while ASA was >> >>> arithmetic, with 400 ASA = 27DIN, 320 ASA = 26 DIN. For every >> step >> >>> the ASA took an arithmetic step, and DIN took a logarithmic step. >> >>> Different measurement methods meant that there wasn't a complete >> >>> equivalency, but then they got together and came out with the ISO >> >>> method and scaling, which allows for both an arithmetic and >> >>> logarithmic scale. So now the old 400 ASA is approximately >> ISO 400/27. >> >>> >> >>> Both systems jump in discrete, defined steps with intermediate >> >>> values undefined. >> >>> >> >> >> >> _______________________________________________ >> >> Leica Users Group. >> >> See http://leica-users.org/mailman/listinfo/lug for more >> information >> > >> > >> > >> > _______________________________________________ >> > Leica Users Group. >> > See http://leica-users.org/mailman/listinfo/lug for more >> information >> > >> >> _______________________________________________ >> Leica Users Group. >> See http://leica-users.org/mailman/listinfo/lug for more information >> > > _______________________________________________ > Leica Users Group. > See http://leica-users.org/mailman/listinfo/lug for more information