Tv Lighting

Fundamentals of TV Lighting Miho Shirakawa NHK Broadcast Engineering Department Content Production Engineering Center (Production Engineering I) training material ©NHK 2007

What is “LIGHTING”

?

LIGHTING is Like drawing pictures with light and shadow

example Johannes Vermeer van Delft “The Kitchen Maid”

training material ©NHK 2007

Classification of Lighting Street Lighting Daily Life Lighting

Office Lighting Room Lighting Signboard Lighting

LIGHTING Television Lighting Stage Lighting

Amusement Lighting Movie Lighting Photograph Lighting training material ©NHK 2007

To Watch Something Incident light retina lens

Optic Nerve Image

Reflected light

Object

Eye

Brain

training material ©NHK 2007

Image on TV System Brain

Eye SIGNAL

LIGHT

LIGHT

SIGNAL NHK

Camera training material ©NHK 2007

Monitor

For TV Lighting Understanding of the Characteristics on

・ TV Camera ・ Light

training material ©NHK 2007

To know TV Camera • Sensitivity 2000 lx / F8

• Resolution 1080i, 720p

• Others on each camera Lens, S/N, etc. training material ©NHK 2007

To Understand Light ① Visible Light ② Luminous Intensity ③ Illuminance ④ Color Temperature ⑤ Color Rendering Index

training material ©NHK 2007

White Light Spectrum

training material ©NHK 2007

Visible Light

380 nm

750 nm

training material ©NHK 2007

Luminous Intensity The luminous flux emitted from a point per unit solid angle into a particular direction.

Official base unit for light

1/683 [W/sr]

Intensity of illuminant

1 [cd] =

540×1012 [Hz]

training material ©NHK 2007

Illuminance The total amount of visible light illuminating a point on a surface from all directions above the surface.

at a point on a surface

Illuminant

[lx]

Object

illuminated intensity of a surface training material ©NHK 2007

Illuminance (E) I

[cd]

θ D [m] Point Source Object Surface

E = I cosθ / D2 [lx] training material ©NHK 2007

Typical Illuminance Values INSIDE PLACE Living Room

OUTSIDE PLACE

[lx]

300 - 700

Office Room 300 - 700

[lx]

Plain Sunshine ～105 Cloudy Sky

～102

Operating Table

20,000 ～

Evening

1～10

Auditorium

70 - 150

Full Moon

～10-1

Half Moon

～10-2

Star Night

～10-3

(theatre)

Restaurant

300 - 700

Shop Front

1500 – 3000

Cf. イメージセンサの イメージセンサの基礎 基礎と と応用, pp. 20 基礎

training material ©NHK 2007

Colour Temperature The absolute temperature of a blackbody radiator having a chromaticity equal to that of the light source

Black Body

heated

heated, heated, ・・・・・

The colour temperature is low.

heated

The colour temperature is high.

training material ©NHK 2007

Correlated Colour Temperature (CCT)

warmer

[K]

Standard Setting

colder

absolute zero temperature

training material ©NHK 2007

CIE Standard Illuminant Illuminant A

2854 [K] tungsten lamp

Illuminant series C filtering illuminant A Illuminant series D natural daylight Illuminant series F

Fluorescent lamp

CIE Standard Illuminant Illuminant A Illuminant D50 (5000 [K] for daylight and fluorescent lighting) Illuminant D65 (6500 [K] for daylight and fluorescent lighting) training material ©NHK 2007

CCTs of Illuminants Illuminant

[K]

Fire of Candle

1900

Studio Tungsten Lamp

3000 ～ 3200

Fluorescent Lamp

3200 ～ 7500

Metal Halide Lamp

5600 ～ 6000

Mercury Lamp

5800

Xenon Lamp

6000 training material ©NHK 2007

Natural Light Illuminant

[K]

Sunrise, Sunset

2000 ～ 3000

Plain Sunshine

5700

Summer Sunny Sky

5500 ～ 6500

Summer Shade

6000 ～ 7000

Overcast Sky

6800 ～ 7000

Clear North Sky

10000 ～ 20000 training material ©NHK 2007

Spectral Sensitivity Curve of Illuminants （ ％） Relative energy

Incandescent lamp

Daylight

Metal halide lamp

Wavelength [ｎｍ ｎｍ] ｎｍ training material ©NHK 2007

Correlated Color Temperature (CCT) CIE (1931) xy chromaticity diagram

D65

training material ©NHK 2007

Wavelengths of monochromatic light are shown in blue.

CCT CIE (1931) xy chromaticity diagram

high colour temperature

low colour temperature

slight change of CCT

significant change of CCT

training material ©NHK 2007

Mired Mired (M) : micro reciprocal degree

M=

106 T [K]

[mired] T [K] color temperature

examples :

Blue Sky 25000 K Flash (photos) 5000 K

training material ©NHK 2007

40 mireds 200 mireds

Colour Temperature Conversion Daytime

Evening

6300 K

3400 K

159 mired

294 mired

+135 mired training material ©NHK 2007

Conversion at Studio Daytime

Evening

135 mired

Studio Tungsten Lamp

2232 K

3200 K

313 mired +135 mired = 448 mired training material ©NHK 2007

Color Conversion Filter A series : Decrease in CCT B series : Increase in CCT

training material ©NHK 2007

Colour Conversion Filters Filters of Tokyo Butaishomei CO., LTD No.

mired

Conversion [K]

No.

mired

Conversion [K]

A1

20

5500 → 5000

B1

-10

3200 → 3300

A2

40

5500 → 4500

B2

-30

3200 → 3500

A3

70

5500 → 4000

B3

-56

3200 → 3900

A4

100

5500 → 3600

B4

-81

3200 → 4300

A5

131

5500 → 3200

B5

-112

3200 → 5000

* See Each Specification. * Mired values are not in common. training material ©NHK 2007

Filter Attachment Daytime

Evening

135 mired

Tungsten Lamp

3200 K

+

A5 Filter

training material ©NHK 2007

Question To mach a halogen lamp of 3200 K into the room with fluorescent lamp of 4300 K, which conversion filter should be used?

training material ©NHK 2007

Allowable Range of CT Human Eye

TV Camera NHK

5 mired

20 mired training material ©NHK 2007

Allowable Range Chart ILLIMINANT

3200 K

6500 K

SENSOR

Human Eye 5 mired

+ 50 K - 50 K

+ 200 K - 200 K

Film 10 mired

+ 200 K - 100 K

+ 500 K - 400 K

TV Camera 20 mired

+ 250 K - 200 K

+ 1000 K - 750 K

training material ©NHK 2007

A Red Apple?

Yes! Red Apple!

It looks yellowish.

training material ©NHK 2007

Color Rendering A characteristic of a light source on the color appearance of objects, compared to natural light.

• Good performance in Colour Rendering Ex. Tungsten Lamp • Bad performance in Colour Rendering Ex. Fluorescent lamp, Mercury Lamp training material ©NHK 2007

Color Rendering Index (CRI) A method for describing the effect of a light source on the color appearance of objects, compared to a reference source of the same color temperature.

Best Condition

Poorest

CRI of 100

CRI of 0

incandescent lamp

training material ©NHK 2007

low-pressure sodium vapor lamp

Illuminant Spectral Sensitivity

Quantum Efficiency [%]

Quantum Efficiency [%]

Sunshine

Wavelength [nm]

Sodium lamp Quantum Efficiency [%]

Incandescent lamp

Wavelength [nm]

training material ©NHK 2007

Wavelength [nm]

CRI i : particular sample colour 4.6 : factor chosen that the Ra of a standard warm-white Thalium lamp would be about 50 ⊿Ei : distance

“Perfect” Source CCT ≦ 5000 K : generally a black body radiator CCT ＞ 5000 K : simulated daylight (e.g. D65) training material ©NHK 2007

General Color Rendering Index

(Ra) An averaged CRI of eight standardized colors chosen to be of intermediate saturation and spread throughout the range of hues.

training material ©NHK 2007

8 Test Colors for Ra No. Colour appearance under daylight 1

CIE test color samples

2

Light greyish red Dark greyish yellow

3

Strong yellow green

4

Moderate yellowish green

non-saturated colors

5

evenly distributed over the complete range of hues

6 7

Light bluish green Light blue Light violet

8

Light reddish purple

cf. JIS (Japanese Industrial Standard)

training material ©NHK 2007

Extra Test Colors To supply extra information No. Colour appearance under daylight 9

CIE test color samples

Strong red

10 Strong yellow cf. JIS (Japanese Industrial Standard)

11 Strong green 12 Strong blue

Our extra … 15 : Light Yellowish pink (Japanese human complexion)

13 Light yellowish pink (human complexion) 14 Moderate olive green (leaf green)

training material ©NHK 2007

Example of Ra Light Source Sun Light (zenith) Tungsten Bulb Halogen lamp Metal Halide Lamp White Fluorescent Lamp High Colour Rendering Fluorescent Lamp Low Pressure Sodium Lamp

training material ©NHK 2007

Ra 100 100 100 70 - 96 61 90 - 99 0

Missions ① Optimise Illuminance ② Balance Contrast ③ Correct Colour Balance ④ Appear Solidity ⑤ Express Texture ⑥ Express Feeling training material ©NHK 2007

① Optimise Illuminance Incident light

Adjustment 83 % Object

100 %

Reflected light

NHK

TV Camera

training material ©NHK 2007

Signal

Adjusted Signal Signal Output 100 % Reflectance 83 %

training material ©NHK 2007

Iris and Optimised Illuminance f/# f/#

= focal length / aperture diameter

2

2.8

4

5.6

Illuminance [lx]

8

11

2000

E = I cosθ / D2 [lx]

Standard Camera Sensitivity

training material ©NHK 2007

16

② Balance Contrast

training material ©NHK 2007

③ Correct Color Balance • Color Temperature of Light Sources Fluorescent Lamp? Tungsten Bulb?

• White Balance of Camera Reconstructed Image of RGB signals

training material ©NHK 2007

Color Balance Fluorescent Lamp Correct Colour Balance 4000 K

example

example

3200 K

Illuminant : Daylight CCT : 5500 K

Tungsten Bulb

example training material ©NHK 2007

④ Appear Solidity Which does appear solidity?

Balance between Light and Shadow training material ©NHK 2007

⑤ Express Texture

Juicy Pork

Comparison with grains

training material ©NHK 2007

⑥ Express Feeling

training material ©NHK 2007

Hard shadow and soft shadow Point light Parallel light Source of light with narrow area Source of light with wide area

training material ©NHK 2007