Richard Knoppow (dickburk@ix.netcom.com)
Wed, 19 May 1999 17:40:02 -0700
At 04:45 PM 5/19/99 +0000, you wrote:
>At 11:39 AM 5/19/99 -0700, Gary Miller wrote:
>>Speaking of the difference of shooting outdoors as opposed to shooting in
>>the studio, why are the outdoors negatives so much more dense. If I am
>>taking a meter reading both inside and outside shouldn't the negatives
>>ultimately be the same density if I am rating the film at the same ASA. I
>>know that Carl has mentioned the difference between using a spot meter
>>reading outdoors as opposed to a flash meter reading in the studio. But
>>shouldn't it all be relative? My shoots from outside are much more dense and
>>stained than my studio shots.
>
>
>Gary,
>It's my understanding that film speeds are slower indoors typically by a
>stop or so as compared to their rated outdoor speed. I don't know why,
>but I'm sure that someone on the list will explain.
>
>John Erbes
>
For panchromatic emulsions the difference in speed between daylight and
tungsten is no more than half a stop. In the days when films carried
separate daylight and tungsten ratings the tungsten rating was typically
the next lower film speed. Ortho films will be about a full stop slower for
tungsten light.
If you are using strobe, there should be no speed difference, at least
due to spectral sensitivity. There may be some reciprocity failure with
some strobes which have very fast flash times. Most modern strobes have
durations of more than 1/1000sec and don't suffer from this.
If you are getting consistent gross differences in exposure indoors, even
with tungsten light, it is more likely to be a problem with metering than
due to the spectral characterics of the film.
----
Richard Knoppow
Los Angeles,Ca.
dickburk@ix.netcom.com
This archive was generated by hypermail 2.0b3 on Thu Oct 28 1999 - 21:39:34