Junkman,
That's the best explanation I've heard so far. Makes perfect sense.
Gene
[EMAIL PROTECTED] wrote:
>
> Dear Gene:
> I'm no scientist in the physics of light propagation. But as I
> understand it,
> it has more to do with the way in which the rays of light are sent
> through
> the plane of the negative. Condensers are designed to arrange the rays
> more
> or less parallel to each other, and diffusion tends to scatter the
> light rays
> helter-skelter. With diffusion, eventually, some of the rays will pass
>
> through the plane of the negative, but at differing angles, hence,
> fewer rays
> of light are hitting the exact same dust speck at the exact same
> angle, and
> some will get through, or under, or around the speck. Therefore, they
> tend
> to 'cancel out' the effect of a dust speck's shadow in the light
> column. A
> condenser, on the other hand, is the antithesis of this concept. When
> you
> have light rays aligned together, many of them will be blocked by that
> dust
> speck, so more shadow effect. Once the light has passed through the
> negative,
> the optics take care of the light from there on. Why this causes the
> noticeable difference in contrast seems to be as a result of the fact
> that in
> one case, as with the condensers, the arraigned rays of light tend to
> pass
> through the negative more evenly, just the opposite of what you would
> expect
> of diffusion. Less scatter with condensers, so equals greater
> contrast.
> (Remember flare in a camera? Reduces contrast) With diffusion, the
> very
> surface of the negative will tend to reflect some of the light rays,
> (That
> is, more so compared to condensers) and you have scatter, otherwise
> known as
> flare. So it;s a trade off. I have tried to get the best of both
> worlds, by
> using diffusion both above and below the condensers... Don't waste
> your time.
> Diffusion above the condensers makes little, if any difference...
> Don't even
> think of putting a diffuser below the condensers... You might as well
> take
> the condensers out, for all the good that does. The diffuser defeats
> the
> purpose of the condensers. It is nice to have a choice... If you have
> some
> negs that are not quite perfect, you might want to use the diffuser,
> and
> condensers the rest of the time. All of this, of course, assumes you
> are
> using the same light source. If you can change from a cold head to a
> tungsten
> lamp, or other light source, then we aren't comparing apples to apples
>
> anymore. I'm sure someone on this list can give you a more technical,
> and
> correct explanation, but this is just what I have found to be the case
> in my
> own experiments. (Read: made a lot of mistakes!) Hope this helps some.
>
> Junkman
> "Mistakes are what I'm making when I'm doing 'Research' "
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