[alt-photo] Re: Ultra Long Exposure Reciprocity Failure?

[Francesco Fragomeni]

Hi everyone,

Thanks for the information and insight. I wanted to offer a quick
clarification so that everyone is on the same page as I am when I say
"ultra long exposures". I'm talking about exposures well beyond hours. I'm
referring to exposures in the duration of weeks, month, and even years. The
extreme nature of such exposures is what led me to believe that there may
be a possibility that reciprocity failure behaves differently or becomes
irrelevant entirely with such long exposures. I've done pinhole exposures
and lensed long exposures into the hours before without much problem
(mainly based on the times that others have provided or basic guesswork
based on manufacturer datasheet info) but I'm talking about going into a
whole different realm of long exposure.

Michael Wesely's work work documenting urban development such as the
re-building of the MOMA building in NY were indeed ultra long exposures and
not time lapse. The MOMA images were 34 month exposures through 4 pinhole
cameras. MOMA invited him to do this project and authorized designated
areas for his cameras so that they could be insured the cameras would not
be disturbed during the ultra long exposures. In some of the images where
the sky is visible you can see the progression of the sun. These images
would in fact be considered Solargraphs on film I suppose. The progression
of the sun's path is continuous and you can see the changes in season as
well as when weather was clear vs overcast. It is textbook Solargraphy.
Other images do not include a view of the sun and this confirms that such
long exposures can be made without view of the sun. Remember, in my
original post I was wondering if the extreme brightness of the sun played
some role in the exposure of paper in Solargraphy. Wesely is using film I
believe but I haven't been able to confirm that. He might have used paper
which would have made reciprocity irrelevant but the images look more like
film then paper to me.

-Francesco Fragomeni
www.francescofragomeni.com




On Fri, Jan 20, 2012 at 5:46 AM, Diana Bloomfield <
dhbloomfield at bellsouth.net> wrote:

> Francesco,
>
> I've only used very long exposures with pinhole cameras as well.  Of
> course, there are published reciprocity charts out there.  (Check Eric
> Renner's 'Pinhole Photography: Rediscovering a Historic Technique').
>  Although his published charts include only pinhole F-stops, I still think
> you could glean something from them.  And I do think that the information
> that comes with film (or used to?) is fairly accurate-- at least for me.
>
> But from my experience, I agree with Gord here that some films "don't seem
> to vary significantly past a certain duration of exposure."  That's
> certainly been my experience (and not just with this high contrast film).
>
> I will also add that the published reciprocity charts I used never seemed
> to offer all that much help to me.  I typically base my long exposures on
> the type of film, the type of (pinhole) camera I'm using, and the available
> light-- basically calculated guesswork, erring on the side of
> over-exposure.  (Quite scientific!).  But with the right development,  I
> never seemed to have a problem.
>
> Diana
>
>
> On Jan 19, 2012, at 11:53 PM, Gordon J. Holtslander wrote:
>
>  I can't offer any mathematical insights,  however the pinhole camera on
>> film work I have done usually involves long exposures.
>>
>> I started doing pinhole work with large format high contrast contact
>> printing film and processed it with Dave Soemarko's LC1 developer mixed to
>> minimize contrast in order to get a continuous tone negative.
>>
>> When used with this developer the film has an effective ASA of 1.  Shots
>> taken outside on a cloudy day would need an exposure of 1/2 hour.  I also
>> took a series of indoor photos where the exposure time as in the range of 6
>> to 8 hours.  As long as I metered accurately my exposures were consistent
>> regardless of the exposure time - from 15 minutes in full sun to 8 hours
>> inside.
>>
>> Used in this way the film (at the time Kodak CGP) did not seem to exhibit
>> any reciprocity failure, or perhaps the reciprocity failure did not vary in
>> the range of exposure I was working with.
>>
>> My point is that perhaps with extremely long exposures the sensitivity of
>> this film is consistent, and does not vary significantly past a certain
>> duration of exposure.
>>
>> It was possible to get reciprocity compensation data for certain film. I
>> don't think is was calculated, but done by empirical testing of each type
>> of film.
>>
>> Try doing some empirical testing and see if your film shows a continually
>> increase in reciprocity failure, or if it stops or decreases after a
>> certain.
>>
>> Photograph a grey scale in dim conditions and increase the exposure time
>> and see what effect it has.
>>
>> I also read that when electronic flashes were first used, some films
>> suffered from reciprocity failure due to extremely short exposure times.
>>
>> Hope this helps.
>>
>> Gord
>>
>
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