Archived posting to the Leica Users Group, 2006/12/09
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Steve Might better ask if meters and shutters are accurate enough to make a difference. Don't know what kind of eye could readily spot 1/3 of a stop? Steve Barbour wrote: > > 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. > > > > btw, is the latitude of this film so narrow/sensitive that shooting > at ISO 320 rather than 400 makes a visible difference? > > thanks, 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 > > > > _______________________________________________ > Leica Users Group. > See http://leica-users.org/mailman/listinfo/lug for more information >