American Cinematographer - August 2017 - 34

*|*

Inside Panavision's Optical Engineering

ASC

associate member and
Panavision's vice president of
optical engineering and lens strategy,
Dan Sasaki, was initially surprised by
how committed the filmmakers were to
featuring Imax footage in Dunkirk, and
particularly by their pursuit of Imaxcaptured footage from inside the cockpits of small Spitfire airplanes. With the
latter directive, Sasaki launched a
project to build "a periscope that can go
on the camera and pan, with a mechanically compensated imaging orienting
prism," he says. Panavision ultimately
engineered six versions of two different
periscopes - including one to acquire
the POV of the water from a boat or
submarine - to meet Hoyte van
Hoytema, ASC, FSF, NSC's specifications.
Panavision also customized two
new sets of Sphero 65 lenses for the
Panavision HR 65mm camera system,
including creating four new focal
lengths (29mm, 40mm, 100mm and
300mm); customized an existing 50mm
(T2) Imax lens originally built for The
Dark Knight (AC July '08); and repaired
director Christopher Nolan's personal
80mm (T2) Imax lens. The company
then developed from scratch additional
50mm (T2) and 80mm (T2) Imax
lenses.
Designing the Periscopes
Dan Sasaki: Hoyte revealed to
me that their original idea of putting a
periscope on a camera supported by a
large ball-bearing turret mechanism,
which would rotate the camera, didn't
pan out - and that by the way, they
were talking about an Imax camera, not
the smaller 5-perf camera. We had been
planning a periscope design based on
the other presumption. As a result of
collaborating with Hoyte, we had to
add another degree of periscope articulation to allow the camera to follow the
other airplanes from inside the cockpit

34

August 2017

more dynamically. The final result gave
us an Imax-specific periscope that not
only tilts, but pans.
Basically, we did a lot of napkin
drawings to figure out if we could pipe
enough light through the system to
achieve Hoyte's target stop of T8. The
clock was ticking and there was no time
to generate an entirely new orienting
prism system. Our solution was to
design around the prism assembly, and
brute-force the optics to complement
the existing light path. Once we solved
the orientation, rotation and stop
requirements, Hoyte discovered that the
system, with Preston motors installed,
was too tall to fit into the cockpit, and
could not get the full axial adjustments
required to capture airplanes flying by.
We were able to get the specs of
the airplane, and that last bit of information directed us into other design
concepts that are used in surveillance
aircraft. We learned that if we
approached the solution with a nonconventional relay system, we could
remote the pupil position of relays and
actually achieve a smaller periscope that
met the T8 requirements, while still
having all the articulated motions
Hoyte required.
Another thing Hoyte asked for
was an optional wider-objective lens to
achieve a more expansive field of view.
The original periscope had an objective
lens that had a field of view equivalent
to 120mm in Imax, which is pretty
wide, approximately a 35mm in the
Super 35 world. But Hoyte requested
an additional lens that would produce
an equivalent field of view of a 17mm in
the Super 35 world, which I think was a
50mm in the Imax world. In creating
this iteration, we actually reduced the
size of the primary front objective to
yield a system that could fit within the
Spitfire.

American Cinematographer

*|*

Creating, Customizing and
Rebuilding Lenses
Sasaki: The tweaks on the existing lenses included readjusting flange
depth, rebuilding mechanical transports and resetting element positions.
In the case of the lenses we had to
build, the 50s are a proprietary design
for Panavision, so we had to pull out old
designs we hadn't addressed since The
Dark Knight Rises [AC Aug. '12], and
remanufacture the glass in a short
period of time.
We basically started over again
with the 80mm lenses as well. One
problem with the 80mm design was
some of the elements in the reproduction were not exactly the same as in the
original Chris Nolan 80mm lens. We
had to do some work with the optical
characteristics of the new batch to get
them to match as close as possible.
For the 65mm 5-perf camera
optics, we had just finished working
with Bob Richardson [ASC] on Live
by Night, and we adapted the Sphero 65
lens technology we developed for that
show to work with film cameras and
their spinning mirrors. One thing
worth noting is that the actual performance of the Sphero 65 lenses had to
be an order higher in performance than
the Imax lenses. That is because of the
blowup factor and lack of magnification
associated with 5-perf 65mm when
compared to native 15-perf Imax. Since
Nolan didn't want there to be a
contrasting look [between the two
formats], we had to be careful about
monitoring performance qualifications
of the new optics. Some of the older
65mm-format lenses didn't have the
pop to match the Imax images
adequately, so we turned to the Sphero
65 lineup and created the four new
focal lengths.
-Michael Goldman



Table of Contents for the Digital Edition of American Cinematographer - August 2017

Contents
American Cinematographer - August 2017 - Intro
American Cinematographer - August 2017 - Cover1
American Cinematographer - August 2017 - Cover2
American Cinematographer - August 2017 - 1
American Cinematographer - August 2017 - 2
American Cinematographer - August 2017 - Contents
American Cinematographer - August 2017 - 4
American Cinematographer - August 2017 - 5
American Cinematographer - August 2017 - 6
American Cinematographer - August 2017 - 7
American Cinematographer - August 2017 - 8
American Cinematographer - August 2017 - 9
American Cinematographer - August 2017 - 10
American Cinematographer - August 2017 - 11
American Cinematographer - August 2017 - 12
American Cinematographer - August 2017 - 13
American Cinematographer - August 2017 - 14
American Cinematographer - August 2017 - 15
American Cinematographer - August 2017 - 16
American Cinematographer - August 2017 - 17
American Cinematographer - August 2017 - 18
American Cinematographer - August 2017 - 19
American Cinematographer - August 2017 - 20
American Cinematographer - August 2017 - 21
American Cinematographer - August 2017 - 22
American Cinematographer - August 2017 - 23
American Cinematographer - August 2017 - 24
American Cinematographer - August 2017 - 25
American Cinematographer - August 2017 - 26
American Cinematographer - August 2017 - 27
American Cinematographer - August 2017 - 28
American Cinematographer - August 2017 - 29
American Cinematographer - August 2017 - 30
American Cinematographer - August 2017 - 31
American Cinematographer - August 2017 - 32
American Cinematographer - August 2017 - 32a
American Cinematographer - August 2017 - 32b
American Cinematographer - August 2017 - 32c
American Cinematographer - August 2017 - 32d
American Cinematographer - August 2017 - 33
American Cinematographer - August 2017 - 34
American Cinematographer - August 2017 - 35
American Cinematographer - August 2017 - 36
American Cinematographer - August 2017 - 37
American Cinematographer - August 2017 - 38
American Cinematographer - August 2017 - 39
American Cinematographer - August 2017 - 40
American Cinematographer - August 2017 - 41
American Cinematographer - August 2017 - 42
American Cinematographer - August 2017 - 43
American Cinematographer - August 2017 - 44
American Cinematographer - August 2017 - 45
American Cinematographer - August 2017 - 46
American Cinematographer - August 2017 - 47
American Cinematographer - August 2017 - 48
American Cinematographer - August 2017 - 49
American Cinematographer - August 2017 - 50
American Cinematographer - August 2017 - 51
American Cinematographer - August 2017 - 52
American Cinematographer - August 2017 - 53
American Cinematographer - August 2017 - 54
American Cinematographer - August 2017 - 55
American Cinematographer - August 2017 - 56
American Cinematographer - August 2017 - 57
American Cinematographer - August 2017 - 58
American Cinematographer - August 2017 - 59
American Cinematographer - August 2017 - 60
American Cinematographer - August 2017 - 61
American Cinematographer - August 2017 - 62
American Cinematographer - August 2017 - 63
American Cinematographer - August 2017 - 64
American Cinematographer - August 2017 - 65
American Cinematographer - August 2017 - 66
American Cinematographer - August 2017 - 67
American Cinematographer - August 2017 - 68
American Cinematographer - August 2017 - 69
American Cinematographer - August 2017 - 70
American Cinematographer - August 2017 - 71
American Cinematographer - August 2017 - 72
American Cinematographer - August 2017 - 73
American Cinematographer - August 2017 - 74
American Cinematographer - August 2017 - 75
American Cinematographer - August 2017 - 76
American Cinematographer - August 2017 - 77
American Cinematographer - August 2017 - 78
American Cinematographer - August 2017 - 79
American Cinematographer - August 2017 - 80
American Cinematographer - August 2017 - Cover3
American Cinematographer - August 2017 - Cover4
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