Diffusion
& Softening filters
by J. Ramón Palacios
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DIFFUSION
AND SOFTENING FILTERS
You may have wondered
what are these filters for and what is the difference between
the two.
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| My wife and elder
grandson with Nikon Soft 1 |
Both "diffusion" and "softening"
filters are used towards the same objective: to reduce blemishes
and wrinkles in portraiture. Make people look better. The
soft filter is just a more elaborated diffusion lens.
DIFFUSION FILTERS
Before these were
mass produced, we placed a stretched fine mesh stocking in
front of the lens. What this did was to bend a certain percentage
of the light forming the image from its original path and
thus defocused it. More recently, these can be obtained as
standard optical glass filters, like the Tiffen Softnet series.
These function through "selective diffusion." They have a
greater effect on small details, such as wrinkles and skin
blemishes, than on the rest of the image. The clear spaces
in the mesh transmit light unchanged, preserving the overall
sharp appearance of the image.
Instead of thinking it through (as we should have all done),
it was through plenty of experimentation -and anger from our
sisters watching their stockings disappear- that we discovered
that the finer the mesh, the more the image area was covered
by mesh lines and therefore had a greater effect. Contrast
was of course reduced and for high speed B&W film photography
it looked very fancy.
Another way to obtain
diffusion was to place a glass, in front of the lens, smeared
with Vaseline. I built several -very heavy- metal contraptions
that attached to the tripod socket of the camera, extending
a bracket to the front beyond the lens to hold a window frame,
where a flat sheet of glass could be slided from the top.
We soon found out that leaving the center clear looked even
better, more romantic, by isolating the subject from its surroundings.
Eventually all of this came to the ears of manufacturers and
now we can buy commercial Center-Spot screw-in diffusion filters.
Hoya, for example,
achieves the diffusion through an irregular uneven surface.
Cokin's Diffusers 083 or 084 are other alternatives.
A popular type are
the concentric ring softeners or Dutto filters; they look
like water after you drop a stone into it. Examples of this
type are the B+W Soft Focus 1 and 2 and the Marumi Diffuser.
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