Re: Home made Lenses ( soft focus )

From: John Cremati ^lt;[email protected]>
Date: 03/04/05-01:33:45 PM Z
Message-id: <000d01c520f1$152b65e0$c5a551d1@k1t0l0>

The older soft focus lenses, like my/your Wollensak Veritars, are
> really just a couple diopters. Very simple two element lenses. A
> diopter is simply a single lens element. This, given the current
> pricing madness, is the joy of John's article. They are simple and
> cheap to build!

Tom,
        I believe the commercial Soft Focus Lenses go far beyond the
mounting two or 3 diopter lenses in a barrel.... As a example the lens which
I had purchased is a color corrected Wollensak Veritar. It is a 3
element design engineered to reduce chromatic aberration , so it is
suitable for color. It achieves its softness by controlled Spherical
aberration... Yet it is free from distortion....The lenses is also coated
for added brilliance...... This lens is a mechanical focus type where what
you see on the ground glass is what you get......A chemical focus lens is a
lens that has to be back focused to compensate for what the film or process
sees.......Sort of like shooting UV film... The film will see something
different other than what is focused on...... Many of the SF lenses are of
this design........
      The chromatic aberration control is achieved both by lens design as
well as the actual raw material the lens is made of so they vary the
diffractive index of the different glass lenses to bring the colors
together.........
   A great book " Professional Portrait Lightings " by Charles Abel lists
about 100 different portraits using various SF lenses..... The differences
between the images are dramatic at times .... Of course the printing
process is a big factor, lighting as well, but the lens differences are
notable.....
     I agree, most of the SF lenses are very simple lenses with 2 or 3
elements , but the effects of each manufactured lens are unique in the way
they were engineered......
John Cremati
Received on Fri Mar 4 13:31:11 2005

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