GD> I disagree completely. No camera lens can make any difference
GD> whatever in the appearance of the grain from a film negative.
I disagree with you, to an extent.
The lens _might_ have some effect on the grain of the
negative, in theory. But if that effect is worth it and visible in
even highly controlled technical shooting is arguable.
Quoting Erwin Puts (which admitedly is not a best source, but for the
topic of this discussion, it is interesting):
> A most interesting phenomenon became visible with these
> side-by-side-shots. The Skopar gives images with a grainier pattern
> and with grain clumps that are rougher than when the Leica lenses
> are used. This is caused by the higher aberration content of the
> Skopar lens. When aberrations are abundant the light rays emanating
> from a light point source do not converge to one point in the image
> but have a more random pattern around the central core. These more
> widely spread rays energise more silver grainaround the center spot
> and randomly so. A rough clumping is the result.
At least half of what he says here is truth ;-) If I remember the
theories well, photons coming from lens falling on film form not a
single point, but something similar to drop falling in water -
sometims even with the core of the circle lower intensity than the
"ripples" - circles around it. All depending on aberration
correction of the lens. An ideal lens would project only the bright
core, a good lens will project a core of small size with high
intensity and just small faint residual "ripples", a bad lens will project a
large circle with faint core and maybe even brighter big residual
ripples.
Now, photographic film works this way: a silver halide crystal is
struck by light. The single crystal's electron is excited or
whatever, that's not so important and I don't remember it <g>. It
becomes latent. But grain is something different from silver halide
crystals. Grain is what happens when the latent crystals are
"developed". The developer causes clumping of the crystals. No
developer develops just the original excited latent crystal, it always
develops in clumps. These vary in size and shape depending on many
variables including chemistry, agitation even maybe and so and so.
Thus, _depending_ on how the size and shape of the circle of confusion (which
is never a true circle of
equal intensity, as described above!), size and separation of silver
halide crystals, and action of the developer, i.e. how it forms the
clumps, could combine to give difference in final grain pattern.
Of course, this is somewhat speculative, as the effect of different
shapes of circles of confusion from best lenses and worst lenses might
be completely lost by the clumping action of the developer, which
doesn't develop single crystals but clumps of them.
Still, I wouldn't say "No camera lens can make any difference whatever
in the appearance of the grain", like you did ;-) We are getting into
matters that are highly specialised and theoretical even between
scientists, and throwing definitive answers like you did is highly dangerous
when
it is all theories...
Good light!
fra
