Archived posting to the Leica Users Group, 2006/01/10

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Subject: [Leica] Underexposure in Tungsten Light
From: don.dory at gmail.com (Don Dory)
Date: Tue Jan 10 17:22:25 2006
References: <p06230921bfe96e361e17@10.0.1.2>

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
>
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>

Replies: Reply from r.s.taylor at comcast.net (Richard S. Taylor) ([Leica] Underexposure in Tungsten Light)