Re: [Cameramakers] enlarger lenses

[CMills1324]

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' "