[pure-silver] Re: Under exposed frame
- From: "Rob Champagne" <app@xxxxxxxxxxxxxxxxxxxxxx>
- To: pure-silver@xxxxxxxxxxxxx
- Date: Wed, 05 Jan 2005 21:35:34 +0000
You should publish this!
At 05/01/2005 15:15 -0500, you wrote:
>From: Christopher Woodhouse <chris.woodhouse@xxxxxxxxxxxx>
>Subject: [pure-silver] Re: Under exposed frame
>Date: Wed, 05 Jan 2005 17:48:31 +0000
>
>> Above the threshold, the halide system is continuous, irrespective
>> of the emulsion combination.
>
>The threshold effect must be considered at individual crystal level.
>(Sensitometric curve analog I gave is a watered down version.)
>
>In ordinary pictorial print emulsion and developers, individual grains
>are either fully developable or not developable at all. There is very
>little time in transition from the beginning of development to
>completion for a single grain. The difference is whether the grain has
>a development center or not. Enough number of high energy photons must
>hit the crystals in order to make latent image of sufficient silver
>cluster that can act as the development center. Those crystals that
>are not developable after G2 exposure remain below the threshold.
>
>There is some room for stable latent subimage that is not developable,
>especially for print emulsions. Crystals with these remain
>subthreshold but they need fewer photons on average (these are all
>stochastic phenomena, because of quantum nature of photon and the
>limited efficiency of photoelectrons making photolytic silver) to
>become developable. After G2 exposure, the shadow areas have more of
>these guys that can be made developable by very brief G5 exposure.
>
>--
>Ryuji Suzuki
>"Keep a good head and always carry a light camera."
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