[pure-silver] Re: Under exposed frame
- From: Christopher Woodhouse <chris.woodhouse@xxxxxxxxxxxx>
- To: <pure-silver@xxxxxxxxxxxxx>
- Date: Thu, 06 Jan 2005 17:41:26 +0000
That may be so, but ultimately the individual crystals get the same photo
energy and wavelength irrespective of whether the exposure is made from a
pure split grade exposure or the hybrid one you suggest.
Like the discussion about the origin of the universe it is all theory and
speculation. Unless we can have an experiment and actually measure a
difference, it remains speculation. That often marks the difference between
a physicist and an engineer. (ouch, I can see the flame war now!)
If you can propose a scientific method to compare split grade printing with
single filter or hybrid split grade printing ,we can try it out. Otherwise
the discussion will favour those results deduced from existing study and
measurement.
Chris Woodhouse MEng!
On 5/1/05 8:15 pm, "Ryuji Suzuki" <rs@xxxxxxxxxxxxxxx> 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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--
Regards Chris Woodhouse
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