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CAMERA FILTERS © Ira Tiffen
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further aligning the lights in the image with their secondary reflections where possible, can
minimize this problem. In critical situations, it may be best to make use of a matte box with
a tilting filter stage. Tilting filter(s) of good optical quality only a few degrees in such a unit
can divert the secondary reflections out of the lens axis, out of the image, without
introducing unwanted distortion or noticeable changes in the filter's effect.
Custom (Homemade and Field-Ready) Filters
There will be times when you need an effect and don't have time to obtain one
ready-made. Certain effects can be produced that, although different from factory filters,
can be useful in a pinch, or for unusual custom situations. Net diffusion effects can be
produced as they were originally, by stretching and affixing one or more layers of stocking
material to the lens end, held in place with a rubber band. There are also numerous things
you can do if you have a clear filter (or several) available. Petroleum jelly can cause flare
or diffusion, or even some starlike streaks, depending on its application, to a clear filter,
spread with a finger or cloth. The chief benefit here is that the effect can also be applied
only to selected portions of the scene. Breathing on a clear filter can produce interesting,
but temporary fog-like results. Using cut gels can simulate certain gradated filter effects.
When doing this, be sure to keep the filter close to the lens, and use larger lens openings,
to keep the visible edge as soft as possible.
To facilitate making your own filters in certain standard square or rectangular sizes,
Tiffen offers Net Frames. These are unique channeled metal frames that replicate the
outer size and shape of 3x3, 4x4, 4x5.65 or 6.6x6.6 size filters. Use them to stretch one or
more fine nets, or other material, and yet have a filter that can readily fit any standard matte
box. They can be re-used to create new effects over and over again.