American Cinematographer - February 2014 - 25

primes, and a Nikon 17-35mm T2.8 zoom)
and Canon DSLRs (used with Canon EF 2470mm f4 zooms) and camcorders, plus
multiple iterations of antique optical
devices. Altogether, 2,400 hours of footage
was accumulated during the 1,825-day
project, which included 130 days of actual
painting.
Jenison intended to make his own
camera obscura using 17th-century techniques, from firing the glass to grinding it by
hand. "That's the depth of his obsession,"
Kelly marvels. "I collect lenses, but Tim
wanted to make them." For specs, Jenison
turned to Philip Steadman, author of
Vermeer's Camera. Through a geometrical
analysis of six Vermeer paintings, Steadman
established not only the use of a lens, but
the dimensions of The Music Lesson's room,
its vanishing point, viewpoint (i.e., position
of the lens), and focal point. "I verified
Steadman's measurements with Lightwave
3D, and they jibed," says Jenison. "I knew I
needed a focal length of approximately 28
inches. Then, I had to work from the focal
length to the curvature." He also turned to
Renaissance Vision from Spectacles to Telescopes by Vincent Ilardi. "This type of lens
would have been the same used in a telescope, about the same diameter and focal
length," Jenison says of his 4" creation.
"They were everywhere by Vermeer's
time."
The path Jenison followed was a
lens-making method that began in the late
1500s. "Eyeglasses were invented around
1290, and they were made by blowing a
sphere, breaking it and then grinding the
back flat," he explains. "The sphere part of
the lens is very imperfect, and if you put one
in a camera obscura, it would make a really
blurry image. But at the end of the 1500s,
the Germans started grinding the sphere
instead of blowing it, and lenses suddenly
got a lot better." The Germans used a
"lap," a grinding tool shaped like a dish, for
convex lenses, and a cannonball for
concave lenses.
In his warehouse, Jenison sprinkled
glass crystals into his lens mold, then fired
that in a pottery kiln to get the rough
shape. "You could start with a piece of flat
glass, but I did this knowing it would save
time grinding, and also to use imperfect
glass," he says. "Mine had bubbles and

Top: Before tackling his Vermeer, Jenison tests his "comparator mirror" by painting a replica of his
father-in-law's portrait. Bottom: He discusses his experiment with artist David Hockney.

little variations of hardness that affected the
quality of the grind. It had inclusions, like
dirt from the mold. None of these things
mattered a bit for the experiment."
He created some brass laps on a
metal lathe. Then came endless hours of
grinding, with the lens revolving on somewww.theasc.com

thing resembling a potter's wheel. "I used a
big slab of granite, which I put on a table
and spun around," he says. In Vermeer's
time, various grades of wet sand would
have been used to grind, and a diatomaceous earth would have been used to
polish. Jenison permitted himself a halfFebruary 2014

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American Cinematographer - February 2014

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