Archived posting to the Leica Users Group, 2006/01/10
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Don - It's interesting that I only noticed this effect in the last couple of years since I started shooting chromogenic films regularly. My older Tri-X negatives and transparencies (from about 1950 - 1980) never showed this effect. It makes me wonder if the older films had better red sensitivity. And what exposure meter was I using in those years, you ask? Why a Gossen Luna Pro and Weston Master V, of course. :-) It's curious though that in all that time I also used a long list of Pentax and Nikon SLRs with built in meters and never had a problem with tungsten-light exposures with any of them as long as I kept metering area away from light sources. I wonder if the CdS cells in those older cameras had lower red sensitivity than the silicon cells in current models. May not matter. I'll open up a 1- to 1-1/2 stops in the future and I suspect all will be well. Thanks. >Richard, >Buried in all the responses are these two facts. First, film is less >responsive to light as it goes over 500nm. Second, most exposure >meters(silicone and CDS) are non linear in their response to different >frequencies of light: they are more sensitive to light in the higher >frequencies. As and aside, the LunaPro sbc and the Pentax spotmeters >calibrated for zone system work are almost linear in their response to >red(er) light. > >So, when shooting by tungsten light open up at least one stop and possibly >two if we are speaking of red gels in theatrical lighting. This is an area >where experience in the venue will be extremely important. > >Don >don.dory@gmail.com > > >On 1/10/06, Richard S. Taylor <r.s.taylor@comcast.net> wrote: >> >> Following up on comments (on and off-list) by David Cochran, it looks >> like the gray appearance and graininess in some of my recent postings >> is due to simple underexposure. Compared to negatives taken in >> daylight on the same film rated identically, they are very thin. >> >> Osterloh (in "Leica M Advanced Photo School") says that the silicon >> diodes in exposure meters can be fooled by the predominantly red >> character of tungsten light leading to as much as 1/2 EV >> underexposure. My negs look more than 1 EV under. >> >> I'm wondering what the experience of LUG is in dealing with tungsten >> illumination. Do you derate the film? Do something else? >> >> (I know strong light sources can fool the meter and have always tried >> to meter well away from them.) >> >> Many thanks. >> -- >> Regards, >> >> Dick >> Boston MA >> >> _______________________________________________ >> 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 -- Regards, Dick Boston MA