Re: Re: [pinhole-dicussion] Reciprocity Failure (was reciprocal failure)

Another thing to remember about compensating for reciprocity failure is that
over-doing it is vastly preferable to under-doing it. You can still print an
overexposed negative. If underexposed there's nothing to work with. Also,
the reciprocity failure itself buffers errors of overexposure very nicely.
Keep in mind the time relationships. I once did a week long exposure that
was a bit too thin. I then exposed for two weeks and got less than one stop
increase in density. One stop can mean 1/500 second or one weeks difference
in exposure time, depending on circumstance.

----- Original Message -----
From: "George L Smyth" <glsmyth@yahoo.com>
To: <pinhole-discussion@pinhole.com>
Sent: Saturday, November 23, 2002 8:22 AM
Subject: [pinhole-discussion] Re: [pinhole-dicussion] Reciprocity Failure
(was reciprocal failure)

>
> --- karol <dzikamalina@interia.pl> wrote:
> > hi
> > i've got an Zero Image pinhole camera
> > and i've got a question concerning sth called 'reciprocal failure'.
> > In a instruction added to a camera it's written
> > that it means that i need to multiply the speed by 2 when it's
1-2seconds,
> > by 4 when it's 2-4...by 12 when it's more then 10 or sth like this.
anyway
> > it's written in a very simplified way so i'd like to know some details.
the
> > aperture in this camera is 138.
>
> Karol -
>
> What you are referring to is Reciprocity Failure. Film is designed to be
> exposed for a certain period of time, oftentimes 1/10,000 of a second
through 1
> second. When you go outside of this design, the film will not properly
capture
> the image if exposed for this time period. You need to adjust your
exposure to
> compensate for a time outside of the film's design.
>
> Different films have different requirements when referenced in this
context, so
> it isn't as simple as just multiplying the exposure by two (for instance,
Tri-X
> and TMX are dramatically different). Look at the reciprocity failure
> information on the sheet of paper that comes with the film you use, and
adjust
> according to the directions there. If you do not have that paper, enter
> "reciprocity failure" and the film type into Google and find it there.
>
> Cheers -
>
> george
>
> =====
> Handmade Photographic Images - http://GLSmyth.com
> DRiP Investing - http://DRiPInvesting.org
>
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Received on Sat Nov 23 11:32:34 2002