American Cinematographer - June 2018 - 22

Deep Focus
Is Moonlight Blue?
Here's an age-old cinematography
question: What is the color temperature of
moonlight? Is it really blue?
Well, moonlight is sunlight that's
reflected off the surface of the moon, so it's
basically daylight color temperature, but the
moon's surface biases that color. Most scientific sources put the moon's color temperature at 4,100K - which is warmer than typical daylight. So why do we see blue moonlight in movies? Why do people insist that
moonlight is cold?
The answer lies in how human vision

works. In normal well-lit situations - such
as a day exterior - the eye uses photopic
vision, which incorporates the eyes' cones to
process light. The cones are very effective for
color discrimination, and with photopic
vision, color perception is at its best. In very
low light levels, on the other hand, the eye
uses scotopic vision, which uses the eyes'
rods to process light. When only rods are
employed, vision becomes nearly monochromatic.
Moonlight conditions fall somewhere
between the two, in what is called mesopic
vision, where both rods and cones are
employed. In normal cone vision, humans
are most sensitive to yellow-green light,

around 550nm. When rods are employed,
we're actually more sensitive to green-blue
light, lower in spectrum toward 500nm. This
may account for the perception of a cooler
moonlight - that and the effect of the rods
desaturating the color vision of the cones.
Whatever the science says, audiences
have come to accept the convention of blue
moonlight. Filmmakers like James Cameron
are famous for their deep-blue night scenes.
Personally, I favor a more monochromatic or
"steely" night look - something just on the
cool side of neutral.
- JH

best performance is called the "circle of
good definition." The area of the image
circle outside of that good definition is
called "extra covering power."
When you employ a lens that was
designed for a smaller format on a larger
imager, you may have enough extra covering power to fully cover your imager, but
the performance at the edges may be
substantially lower than you would otherwise expect from that lens. However, that's
not necessarily a bad thing! Degradation in
performance can be an artistically desired
effect. It's up to the individual taste of the
cinematographer and director, and the
needs of the particular project.
If the full image circle, including its
extra covering power, isn't sufficient to
cover a given larger imager, there could be
a darkening around the edges, known as
"vignetting," or even complete blackness in
the corners where the circle doesn't cover at
all, known as "portholing."
If you're working with a larger-thanSuper-35 sensor, it becomes incredibly
important to test every lens for yourself so
you'll know for certain not only whether it
covers the sensor/format you'll be using,

but whether its performance edge-to-edge
is acceptable to your tastes. It's imperative
to test every lens, every focal length, every
aperture and the extreme focus distances
- close focus and infinity - as the image
circle can change across all of those parameters.
The diameter of the image circle may
be increased to a degree by opening the
aperture of the lens. When a lens is opened
to its widest aperture it will generally have
its largest overall image circle.
With most lenses, the image circle is
smallest when the lens is focused at infinity,
when the focusing elements are closest to
the imager; as the lens is focused to closer
distances, the image circle may increase in
size as its focusing elements move farther
away from the imaging plane. This is true
for most lenses, but not all of them -
different optical designs use different methods of focusing within a lens.
Longer focal lengths naturally
project a larger image circle. Within a family
of lenses, the wider focal lengths may not
have any extra covering power beyond the
format they were designed for, but the
longer lenses within that same family very

well might. Often focal lengths of 50mm or
longer will have an image circle big enough
to cover an imager larger than what the
lens family is intended for.
This same phenomenon can mean
that the image circle on a zoom lens will
increase as the lens is zoomed toward the
longer end. If you're using a zoom lens on
a larger imager than it was intended for, it's
entirely possible that the wide end of the
lens will vignette or even porthole, but as
you zoom in to longer focal lengths, it may
cover the imager completely.
When choosing a lens, be sure to
determine whether the image circle
projected will cover the imager size you're
going to be using on your particular camera
system.
- JH

Today, the standard image circles required to cover common formats are:
Format
Academy 35
Super 35
Full Frame
65mm

22

June 2018

Sensor Size
21.95mm x 16mm
24.89mm x 18.67mm
36mm x 24mm
52.48mm x 23.01mm

Image-Circle Diameter
27.2mm
31.1mm
43.3mm
57.3mm

American Cinematographer

Portions of this month's Shot Craft
have been excerpted from Holben's book
Behind the Lens: Dispatches From the Cinematographic Trenches.
‚óŹ



Table of Contents for the Digital Edition of American Cinematographer - June 2018

Contents
American Cinematographer - June 2018 - Intro
American Cinematographer - June 2018 - Cover1
American Cinematographer - June 2018 - Cover2
American Cinematographer - June 2018 - 1
American Cinematographer - June 2018 - 2
American Cinematographer - June 2018 - Contents
American Cinematographer - June 2018 - 4
American Cinematographer - June 2018 - 5
American Cinematographer - June 2018 - 6
American Cinematographer - June 2018 - 7
American Cinematographer - June 2018 - 8
American Cinematographer - June 2018 - 9
American Cinematographer - June 2018 - 10
American Cinematographer - June 2018 - 11
American Cinematographer - June 2018 - 12
American Cinematographer - June 2018 - 13
American Cinematographer - June 2018 - 14
American Cinematographer - June 2018 - 15
American Cinematographer - June 2018 - 16
American Cinematographer - June 2018 - 17
American Cinematographer - June 2018 - 18
American Cinematographer - June 2018 - 19
American Cinematographer - June 2018 - 20
American Cinematographer - June 2018 - 21
American Cinematographer - June 2018 - 22
American Cinematographer - June 2018 - 23
American Cinematographer - June 2018 - 24
American Cinematographer - June 2018 - 25
American Cinematographer - June 2018 - 26
American Cinematographer - June 2018 - 27
American Cinematographer - June 2018 - 28
American Cinematographer - June 2018 - 29
American Cinematographer - June 2018 - 30
American Cinematographer - June 2018 - 31
American Cinematographer - June 2018 - 32
American Cinematographer - June 2018 - 33
American Cinematographer - June 2018 - 34
American Cinematographer - June 2018 - 35
American Cinematographer - June 2018 - 36
American Cinematographer - June 2018 - 37
American Cinematographer - June 2018 - 38
American Cinematographer - June 2018 - 39
American Cinematographer - June 2018 - 40
American Cinematographer - June 2018 - 41
American Cinematographer - June 2018 - 42
American Cinematographer - June 2018 - 43
American Cinematographer - June 2018 - 44
American Cinematographer - June 2018 - 45
American Cinematographer - June 2018 - 46
American Cinematographer - June 2018 - 47
American Cinematographer - June 2018 - 48
American Cinematographer - June 2018 - 49
American Cinematographer - June 2018 - 50
American Cinematographer - June 2018 - 51
American Cinematographer - June 2018 - 52
American Cinematographer - June 2018 - 53
American Cinematographer - June 2018 - 54
American Cinematographer - June 2018 - 55
American Cinematographer - June 2018 - 56
American Cinematographer - June 2018 - 57
American Cinematographer - June 2018 - 58
American Cinematographer - June 2018 - 59
American Cinematographer - June 2018 - 60
American Cinematographer - June 2018 - 61
American Cinematographer - June 2018 - 62
American Cinematographer - June 2018 - 63
American Cinematographer - June 2018 - 64
American Cinematographer - June 2018 - 65
American Cinematographer - June 2018 - 66
American Cinematographer - June 2018 - 67
American Cinematographer - June 2018 - 68
American Cinematographer - June 2018 - 69
American Cinematographer - June 2018 - 70
American Cinematographer - June 2018 - 71
American Cinematographer - June 2018 - 72
American Cinematographer - June 2018 - 73
American Cinematographer - June 2018 - 74
American Cinematographer - June 2018 - 75
American Cinematographer - June 2018 - 76
American Cinematographer - June 2018 - 77
American Cinematographer - June 2018 - 78
American Cinematographer - June 2018 - 79
American Cinematographer - June 2018 - 80
American Cinematographer - June 2018 - 81
American Cinematographer - June 2018 - 82
American Cinematographer - June 2018 - 83
American Cinematographer - June 2018 - 84
American Cinematographer - June 2018 - 85
American Cinematographer - June 2018 - 86
American Cinematographer - June 2018 - 87
American Cinematographer - June 2018 - 88
American Cinematographer - June 2018 - 89
American Cinematographer - June 2018 - 90
American Cinematographer - June 2018 - 91
American Cinematographer - June 2018 - 92
American Cinematographer - June 2018 - 93
American Cinematographer - June 2018 - 94
American Cinematographer - June 2018 - 95
American Cinematographer - June 2018 - 96
American Cinematographer - June 2018 - 97
American Cinematographer - June 2018 - 98
American Cinematographer - June 2018 - 99
American Cinematographer - June 2018 - 100
American Cinematographer - June 2018 - 101
American Cinematographer - June 2018 - 102
American Cinematographer - June 2018 - 103
American Cinematographer - June 2018 - 104
American Cinematographer - June 2018 - 105
American Cinematographer - June 2018 - 106
American Cinematographer - June 2018 - 107
American Cinematographer - June 2018 - 108
American Cinematographer - June 2018 - 109
American Cinematographer - June 2018 - 110
American Cinematographer - June 2018 - 111
American Cinematographer - June 2018 - 112
American Cinematographer - June 2018 - 113
American Cinematographer - June 2018 - 114
American Cinematographer - June 2018 - 115
American Cinematographer - June 2018 - 116
American Cinematographer - June 2018 - 117
American Cinematographer - June 2018 - 118
American Cinematographer - June 2018 - 119
American Cinematographer - June 2018 - 120
American Cinematographer - June 2018 - 121
American Cinematographer - June 2018 - 122
American Cinematographer - June 2018 - 123
American Cinematographer - June 2018 - 124
American Cinematographer - June 2018 - 125
American Cinematographer - June 2018 - 126
American Cinematographer - June 2018 - 127
American Cinematographer - June 2018 - 128
American Cinematographer - June 2018 - 129
American Cinematographer - June 2018 - 130
American Cinematographer - June 2018 - 131
American Cinematographer - June 2018 - 132
American Cinematographer - June 2018 - 133
American Cinematographer - June 2018 - 134
American Cinematographer - June 2018 - 135
American Cinematographer - June 2018 - 136
American Cinematographer - June 2018 - Cover3
American Cinematographer - June 2018 - Cover4
http://www.nxtbook.com/nxtbooks/ac/ac0320
http://www.nxtbook.com/nxtbooks/ac/ac0220
http://www.nxtbook.com/nxtbooks/ac/ac0120
http://www.nxtbook.com/nxtbooks/ac/ac1219
http://www.nxtbook.com/nxtbooks/ac/ac1119
http://www.nxtbook.com/nxtbooks/ac/ac1019
http://www.nxtbook.com/nxtbooks/ac/ac0919
http://www.nxtbook.com/nxtbooks/ac/ac0819
http://www.nxtbook.com/nxtbooks/ac/ac0719
http://www.nxtbook.com/nxtbooks/ac/ac0619
http://www.nxtbook.com/nxtbooks/ac/ac0519
http://www.nxtbook.com/nxtbooks/ac/ac0419
http://www.nxtbook.com/nxtbooks/ac/ac0319
http://www.nxtbook.com/nxtbooks/ac/ac0219_v2
http://www.nxtbook.com/nxtbooks/ac/ac0219
http://www.nxtbook.com/nxtbooks/ac/ac0119_v2
http://www.nxtbook.com/nxtbooks/ac/ac0119
http://www.nxtbook.com/nxtbooks/ac/ac1218
http://www.nxtbook.com/nxtbooks/ac/ac1118
http://www.nxtbook.com/nxtbooks/ac/ac1018
http://www.nxtbook.com/nxtbooks/ac/ac0918
http://www.nxtbook.com/nxtbooks/ac/ac0818
http://www.nxtbook.com/nxtbooks/ac/ac0718
http://www.nxtbook.com/nxtbooks/ac/ac0618
http://www.nxtbook.com/nxtbooks/ac/ac0518
http://www.nxtbook.com/nxtbooks/ac/ac0418
http://www.nxtbook.com/nxtbooks/ac/ac0318
http://www.nxtbook.com/nxtbooks/ac/ac0218
http://www.nxtbook.com/nxtbooks/ac/ac0118
http://www.nxtbook.com/nxtbooks/ac/ac1217
http://www.nxtbook.com/nxtbooks/ac/ac1117
http://www.nxtbook.com/nxtbooks/ac/ac1017
http://www.nxtbook.com/nxtbooks/ac/ac0917
http://www.nxtbook.com/nxtbooks/ac/ac0817
http://www.nxtbook.com/nxtbooks/ac/ac0717
http://www.nxtbook.com/nxtbooks/ac/ac0617
http://www.nxtbook.com/nxtbooks/ac/ac0517
http://www.nxtbook.com/nxtbooks/ac/ac0417
http://www.nxtbook.com/nxtbooks/ac/ac0317
http://www.nxtbook.com/nxtbooks/ac/ac0217
http://www.nxtbook.com/nxtbooks/ac/ac0117
http://www.nxtbook.com/nxtbooks/ac/ac1216
http://www.nxtbook.com/nxtbooks/ac/ac1116
http://www.nxtbook.com/nxtbooks/ac/ac1016
http://www.nxtbook.com/nxtbooks/ac/ac0916
http://www.nxtbook.com/nxtbooks/ac/ac0816
http://www.nxtbook.com/nxtbooks/ac/ac0716
http://www.nxtbook.com/nxtbooks/ac/ac0616
http://www.nxtbook.com/nxtbooks/ac/ac0516
http://www.nxtbook.com/nxtbooks/ac/ac0416
http://www.nxtbook.com/nxtbooks/ac/ac0316
http://www.nxtbook.com/nxtbooks/ac/ac0216
http://www.nxtbook.com/nxtbooks/ac/ac0116
http://www.nxtbook.com/nxtbooks/ac/ac1215
http://www.nxtbook.com/nxtbooks/ac/ac1115
http://www.nxtbook.com/nxtbooks/ac/ac1015
http://www.nxtbook.com/nxtbooks/ac/ac0915
http://www.nxtbook.com/nxtbooks/ac/ac0815
http://www.nxtbook.com/nxtbooks/ac/ac0715
http://www.nxtbook.com/nxtbooks/ac/ac0615
http://www.nxtbook.com/nxtbooks/ac/ac0515
http://www.nxtbook.com/nxtbooks/ac/ac0415
http://www.nxtbook.com/nxtbooks/ac/ac0315
http://www.nxtbook.com/nxtbooks/ac/ac0215
http://www.nxtbook.com/nxtbooks/ac/ac0115
http://www.nxtbookMEDIA.com