[pure-silver] Re: History... Clarification

  • From: Jean-David Beyer <jeandavid8@xxxxxxxxxxx>
  • To: pure-silver@xxxxxxxxxxxxx
  • Date: Mon, 19 Oct 2009 11:07:41 -0400

Hash: SHA1

Ray Rogers wrote:
| Hummm... the answer to another question posed in private again answered
| in public... I sense a pattern evolving.

The stuff I answered in public were in reply to the questions asked in public.
| Oh well,
| Two of my attempts having been thus far thwarted, I guess I will give up
| further attempts at "private communciaton". So... here we go public:
| I do appreciate the detailed description of the screens- I don't think
| many photographers ever really grasp how those plates are made... I know
| your description was refreshing for me- to say the least.
| I don't really grasp the physics behind why the diameter of images are
| related to the intensty of the light, unless it involves light "bleed"...

I would not call it that. It is purely a geometric effect with the
wavelengths of light and the pinhole sizes. Much is made about diffraction
here, but it does not matter in practice except in very fine screens. I do
not know if such fine screens were actually used. The aperture size of the
pinholes is somewhere close to where diffraction could be a problem, but in
practice, it does not.

If you consider the geometry of those zillions of pinhole cameras, consider
just one of them. The light that passes through will be brightest at the
center and fall off to the edges. Now the brightness depends on the amount
of light coming through the negative and the lens. So with normal film, that
is what you would see. But if you use high contrast litho film, all
brightness over a certain amount will develop and those less than that will
not. And the brightness is the brightness of that circle (in the case of a
round aperture in the lens).

| but anyway it is a fascnating aspect of photography that I wish I could
| have had a demonstration of way back when I frst began learning about
| photography, or even later, in college, but that is something that I
| missed... even today, I have attended conferences where electronic paper
| was being discussed and, naturally, no one had any samples!
| On the other hand, I have seen some very fine present day collotypes.
| BTW, I am curious... is Jean-David Beyer a male or a female?

I am a man.

| Please note
| that unlke the links you provided concering your relatives, I am not
| asking about sexual orentation... (I don't even know how they presume to
| discern such information, but oh well...) Does the hyphen indicate
| marriage or was it a given name?

It is my given name. Jean-David is French for John-David. I was born in
France and my parents were French citizens at the time, although my mother
was born in Philadelphia, USA.

- --
~  .~.  Jean-David Beyer          Registered Linux User 85642.
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