Category: lighting
Aputure AL-F7 – dimmable Led Video Light, CRI95+, 3200-9500K
High CRI of ≥95
256 LEDs with 45° beam angle
3200 to 9500K variable color temperature
1 to 100% Stepless Dimming, 1500 Lux Brightness at 3.3′
LCD Info Screen. Powered by an L-series battery, D-Tap, or USB-C
Because the light has a variable color range of 3200 to 9500K, when the light is set to 5500K (daylight balanced) both sets of LEDs are on at full, providing the maximum brightness from this fixture when compared to using the light at 3200 or 9500K.
The LCD screen provides information on the fixture’s output as well as the charge state of the battery. The screen also indicates whether the adjustment knob is controlling brightness or color temperature. To switch from brightness to CCT or CCT to brightness, just apply a short press to the adjustment knob.
The included cold shoe ball joint adapter enables mounting the light to your camera’s accessory shoe via the 1/4″-20 threaded hole on the fixture. In addition, the bottom of the cold shoe foot features a 3/8″-16 threaded hole, and includes a 3/8″-16 to 1/4″-20 reducing bushing.
StudioBinder.com – CRI color rendering index
www.studiobinder.com/blog/what-is-color-rendering-index
“The Color Rendering Index is a measurement of how faithfully a light source reveals the colors of whatever it illuminates, it describes the ability of a light source to reveal the color of an object, as compared to the color a natural light source would provide. The highest possible CRI is 100. A CRI of 100 generally refers to a perfect black body, like a tungsten light source or the sun. ”
www.pixelsham.com/2021/04/28/types-of-film-lights-and-their-efficiency
Types of Film Lights and their efficiency – CRI, Color Temperature and Luminous Efficacy
nofilmschool.com/types-of-film-lights
“Not every light performs the same way. Lights and lighting are tricky to handle. You have to plan for every circumstance. But the good news is, lighting can be adjusted. Let’s look at different factors that affect lighting in every scene you shoot. ”
Use CRI, Luminous Efficacy and color temperature controls to match your needs.
Color Temperature
Color temperature describes the “color” of white light by a light source radiated by a perfect black body at a given temperature measured in degrees Kelvin
http://www.pixelsham.com/2019/10/18/color-temperature/
CRI
“The Color Rendering Index is a measurement of how faithfully a light source reveals the colors of whatever it illuminates, it describes the ability of a light source to reveal the color of an object, as compared to the color a natural light source would provide. The highest possible CRI is 100. A CRI of 100 generally refers to a perfect black body, like a tungsten light source or the sun. ”
https://www.studiobinder.com/blog/what-is-color-rendering-index/
https://en.wikipedia.org/wiki/Color_rendering_index
Light source | CCT (K) | CRI |
---|---|---|
Low-pressure sodium (LPS/SOX) | 1800 | −44 |
Clear mercury-vapor | 6410 | 17 |
High-pressure sodium (HPS/SON) | 2100 | 24 |
Coated mercury-vapor | 3600 | 49 |
Halophosphate warm-white fluorescent | 2940 | 51 |
Halophosphate cool-white fluorescent | 4230 | 64 |
Tri-phosphor warm-white fluorescent | 2940 | 73 |
Halophosphate cool-daylight fluorescent | 6430 | 76 |
“White” SON | 2700 | 82 |
Standard LED Lamp | 2700–5000 | 83 |
Quartz metal halide | 4200 | 85 |
Tri-phosphor cool-white fluorescent | 4080 | 89 |
High-CRI LED lamp (blue LED) | 2700–5000 | 95 |
Ceramic discharge metal-halide lamp | 5400 | 96 |
Ultra-high-CRI LED lamp (violet LED) | 2700–5000 | 99 |
Incandescent/halogen bulb | 3200 | 100 |
Luminous Efficacy
Luminous efficacy is a measure of how well a light source produces visible light, watts out versus watts in, measured in lumens per watt. In other words it is a measurement that indicates the ability of a light source to emit visible light using a given amount of power. It is a ratio of the visible energy to the power that goes into the bulb.
FILM LIGHT TYPES
Consumer light types
Tungsten Lights
Light interiors and match domestic places or office locations. Daylight.
Advantages of Tungsten Lights
Almost perfect color rendition
Low cost
Does not use mercury like CFLs (fluorescent) or mercury vapor lights
Better color temperature than standard tungsten
Longer life than a conventional incandescent
Instant on to full brightness, no warm-up time, and it is dimmable
Disadvantages of Tungsten Lights
Extremely hot
High power requirement
The lamp is sensitive to oils and cannot be touched
The bulb is capable of blowing and sending hot glass shards outward. A screen or layer of glass on the outside of the lamp can protect users.
Hydrargyrum medium-arc iodide lights
HMI’s are used when high output is required. They are also used to recreate sun shining through windows or to fake additional sun while shooting exteriors. HMIs can light huge areas at once.
Advantages of HMI lights
High light output
Higher efficiency
High color temperature
Disadvantages of HMI lights:
High cost
High power requirement
Dims only to about 50%
the color temperature increases with dimming
HMI bulbs will explode is dropped and release toxic chemicals
Fluorescent
Fluorescent film lighting is achieved by laying multiple tubes next to each other, combining as many as you want for the desired brightness. The good news is you can choose your bulbs to either be warm or cool depending on the scenario you’re shooting. You want to get these bulbs close to the subject because they’re not great at opening up spaces. Fluorescent lighting is used to light interiors and is more compact and cooler than tungsten or HMI lighting.
Advantages of Fluorescent lights
High efficiency
Low power requirement
Low cost
Long lamp life
Cool
Capable of soft even lighting over a large area
Lightweight
Disadvantages of Fluorescent lights
Flicker
High CRI
Domestic tubes have low CRI & poor color rendition.
LED
LED’s are more and more common on film sets. You can use batteries to power them. That makes them portable and sleek – no messy cabled needed. You can rig your own panels of LED lights to fit any space necessary as well. LED’s can also power Fresnel style lamp heads such as the Arri L-series.
Advantages of LED light
Soft, even lighting
Pure light without UV-artifacts
High efficiency
Low power consumption, can be battery powered
Excellent dimming by means of pulse width modulation control
Long lifespan
Environmentally friendly
Insensitive to shock
No risk of explosion
Disadvantages of LED light
High cost.
LED’s are currently still expensive for their total light output
https://www.artstation.com/marketplace/p/lP0V/hdri-collection-1-23-studio-lights-lamps-and-softboxes
The Color of Infinite Temperature
This is the color of something infinitely hot.
Of course you’d instantly be fried by gamma rays of arbitrarily high frequency, but this would be its spectrum in the visible range.
johncarlosbaez.wordpress.com/2022/01/16/the-color-of-infinite-temperature/
This is also the color of a typical neutron star. They’re so hot they look the same.
It’s also the color of the early Universe!
This was worked out by David Madore.
The color he got is sRGB(148,177,255).
www.htmlcsscolor.com/hex/94B1FF
And according to the experts who sip latte all day and make up names for colors, this color is called ‘Perano’.
Outpost VFX lighting tips
www.outpost-vfx.com/en/news/18-pro-tips-and-tricks-for-lighting
Get as much information regarding your plate lighting as possible
Always use a reference
Replicate what is happening in real life
Invest into a solid HDRI
Start Simple
Observe real world lighting, photography and cinematography
Don’t neglect the theory
Learn the difference between realism and photo-realism.
Keep your scenes organised
7 Easy Portrait Lighting Setups
Butterfly
Loop
Rembrandt
Split
Rim
Broad
Short
Key/Fill ratios and scene composition using false colors
To measure the contrast ratio you will need a light meter. The process starts with you measuring the main source of light, or the key light.
Get a reading from the brightest area on the face of your subject. Then, measure the area lit by the secondary light, or fill light. To make sense of what you have just measured you have to understand that the information you have just gathered is in F-stops, a measure of light. With each additional F-stop, for example going one stop from f/1.4 to f/2.0, you create a doubling of light. The reverse is also true; moving one stop from f/8.0 to f/5.6 results in a halving of the light.
Let’s say you grabbed a measurement from your key light of f/8.0. Then, when you measured your fill light area, you get a reading of f/4.0. This will lead you to a contrast ratio of 4:1 because there are two stops between f/4.0 and f/8.0 and each stop doubles the amount of light. In other words, two stops x twice the light per stop = four times as much light at f/8.0 than at f/4.0.
theslantedlens.com/2017/lighting-ratios-photo-video/
What Can’t Ratios Tell You?
Ratios are great but they don’t solve all the challenges of a lighting set up for a DP. Ratios help with the mood but there are a number of other factors that need to be considered as well.
1. Type of Lighting:
Soft light vs. Hard Light. Ratios can’t help you determine whether to use soft light or hard light. You have to know what the differences are and when to employ them.
2. Direction of Lighting
Ratios can’t help you determine where the Key light should be coming from.
3. Color
Ratios are no good for color. You have to develop your project and understand how the color temperature of lights impacts mood and feeling.
To get the most out of the images below you have to know what you are looking at. The FSI False Color is user adjustable (one of the reasons it is so powerful) and they way I have set it up reads like this.
RED = 3 Stops Over
Yellow = 2 Stops Over
Light Green = 1 Stop Over
Grey = Key
Teal = 1 Stop Under
Light Blue = 2 Stops Under
Dark Blue = 3 Stops Under
Black = 4 Stops Under
Replicating the fake color process through Foundry Nuke:
set cut_paste_input [stack 0]
version 13.2 v7
push $cut_paste_input
Expression {
expr0 "(r > 2) || (g > 2) || (b > 2) ? 3:0"
expr1 "((r > 1) && (r < 2)) || ((g > 1) && (g < 2)) || ((b > 1) && (b < 2))\n ? 2:0"
expr2 "((r > 0) && (r < 1)) || ((g > 0) && (g < 1)) || ((b > 0) && (b < 1))\n ? 1:0"
name Expression4
selected true
xpos 631
ypos 54
}
Blur {
size 100
filter quadratic
name Blur1
selected true
xpos 631
ypos 120
}
Blurring an image using the same scheme:
set cut_paste_input [stack 0]
version 13.2 v8
push $cut_paste_input
Dot {
name Dot27
selected true
xpos 446
ypos 2259
}
set N329d7800 [stack 0]
Expression {
expr0 "(r > 2) || (g > 2) || (b > 2) ? 3:0"
expr1 "((r > 1) && (r < 2)) || ((g > 1) && (g < 2)) || ((b > 1) && (b < 2))\n ? 2:0"
expr2 "((r > 0) && (r < 1)) || ((g > 0) && (g < 1)) || ((b > 0) && (b < 1))\n ? 1:0"
name Expression1
selected true
xpos 521
ypos 2167
}
set N66560500 [stack 0]
Shuffle2 {
fromInput1 {{0} B}
fromInput2 {{0} B}
mappings "4 black -1 -1 rgba.red 0 0 rgba.green 0 1 rgba.alpha 0 3 black -1 -1 rgba.blue 0 2 rgba.green 0 1 rgba.green 0 1"
name Shuffle7
selected true
xpos 621
ypos 2241
}
push $N329d7800
Copy {
inputs 2
from0 rgba.alpha
to0 rgba.alpha
name Copy1
selected true
xpos 621
ypos 2315
}
Blur {
size 50
maskChannelInput rgba.alpha
name Blur3
selected true
xpos 621
ypos 2384
}
push $N66560500
Shuffle2 {
fromInput1 {{0} B}
fromInput2 {{0} B}
mappings "4 black -1 -1 rgba.green 0 1 black -1 -1 rgba.red 0 0 rgba.blue 0 2 rgba.blue 0 2 rgba.blue 0 2 rgba.alpha 0 3"
name Shuffle1
selected true
xpos 730
ypos 2242
}
push $N329d7800
Copy {
inputs 2
from0 rgba.alpha
to0 rgba.alpha
name Copy2
selected true
xpos 793
ypos 2318
}
Blur {
size 100
maskChannelInput rgba.alpha
name Blur4
selected true
xpos 793
ypos 2380
}
Merge2 {
inputs 2
operation matte
name Merge3
selected true
xpos 621
ypos 2459
}
push $N66560500
Shuffle2 {
fromInput1 {{0} B}
fromInput2 {{0} B}
mappings "4 rgba.red 0 0 rgba.red 0 0 rgba.red 0 0 rgba.alpha 0 3 black -1 -1 rgba.blue 0 2 black -1 -1 rgba.green 0 1"
name Shuffle8
selected true
xpos 521
ypos 2241
}
push $N329d7800
Copy {
inputs 2
from0 rgba.alpha
to0 rgba.alpha
name Copy3
selected true
xpos 521
ypos 2315
}
Merge2 {
inputs 2
operation matte
name Merge5
selected true
xpos 521
ypos 2506
}
The two options together
set cut_paste_input [stack 0] version 13.2 v8 push $cut_paste_input Group { name FalseColorCompositionTest selected true xpos 389 ypos 192 } BackdropNode { inputs 0 name VIEWER_1 xpos 458 ypos -174 } BackdropNode { inputs 0 name VIEWER_2 xpos 722 ypos -108 bdwidth 161 bdheight 68 } BackdropNode { inputs 0 name VIEWER_3 tile_color 0x8e8e8eff note_font_size 42 xpos 738 ypos 301 bdheight 110 } BackdropNode { inputs 0 name VIEWER_4 xpos 394 ypos -43 } Input { inputs 0 name Input1 xpos 467 ypos -326 } Dot { name DotIN xpos 501 ypos -258 } Dot { name Dot2 label "\n" xpos 501 ypos -144 } set N28599ad0 [stack 0] Dot { name Dot27 xpos 611 ypos -144 } set N2859e960 [stack 0] Expression { expr0 "(r > 2) || (g > 2) || (b > 2) ? 3:0" expr1 "((r > 1) && (r < 2)) || ((g > 1) && (g < 2)) || ((b > 1) && (b < 2))\n ? 2:0" expr2 "((r > 0) && (r < 1)) || ((g > 0) && (g < 1)) || ((b > 0) && (b < 1))\n ? 1:0" name Expression4 xpos 828 ypos -148 } push $N2859e960 Expression { expr0 "(r > .6) || (g > .6) || (b > .6) ? 3:0" expr1 "((r > .22) && (r < .6)) || ((g > .22) && (g < .6)) || ((b > .22) && (b < .6))\n ? 2:0" expr2 "((r > 0) && (r < .22)) || ((g > 0) && (g < .22)) || ((b > 0) && (b < .22))\n ? 1:0" name Expression1 xpos 710 ypos -186 } Switch { inputs 2 name Switch1 xpos 760 ypos -78 } set N28650240 [stack 0] Dot { name Dot1 xpos 878 ypos 5 } set N286582c0 [stack 0] Shuffle2 { fromInput1 {{0} B} fromInput2 {{0} B} mappings "4 black -1 -1 rgba.red 0 0 rgba.green 0 1 rgba.alpha 0 3 black -1 -1 rgba.blue 0 2 rgba.green 0 1 rgba.green 0 1" name Shuffle7 xpos 844 ypos 41 } push $N2859e960 Copy { inputs 2 from0 rgba.alpha to0 rgba.alpha name Copy1 xpos 844 ypos 115 } Blur { size 100 maskChannelInput rgba.alpha name Blur3 xpos 844 ypos 184 } push $N286582c0 Shuffle2 { fromInput1 {{0} B} fromInput2 {{0} B} mappings "4 black -1 -1 rgba.green 0 1 black -1 -1 rgba.red 0 0 rgba.blue 0 2 rgba.blue 0 2 rgba.blue 0 2 rgba.alpha 0 3" name Shuffle1 xpos 953 ypos 42 } push $N2859e960 Copy { inputs 2 from0 rgba.alpha to0 rgba.alpha name Copy2 xpos 953 ypos 111 } Blur { size 200 maskChannelInput rgba.alpha name Blur4 xpos 953 ypos 173 } Merge2 { inputs 2 operation matte name Merge3 xpos 844 ypos 259 } push $N286582c0 Shuffle2 { fromInput1 {{0} B} fromInput2 {{0} B} mappings "4 rgba.red 0 0 rgba.red 0 0 rgba.red 0 0 rgba.alpha 0 3 black -1 -1 rgba.blue 0 2 black -1 -1 rgba.green 0 1" name Shuffle8 xpos 744 ypos 41 } push $N2859e960 Copy { inputs 2 from0 rgba.alpha to0 rgba.alpha name Copy3 xpos 744 ypos 115 } Merge2 { inputs 2 operation matte name Merge5 xpos 744 ypos 354 } push $N28650240 push $N28599ad0 Saturation { saturation 0 name Saturation1 xpos 398 ypos -15 } push $N28599ad0 ContactSheet { inputs 4 width 6100 height 2501 rows 1 center true name ContactSheet1 xpos 482 ypos 437 } Dot { name DotOUT xpos 512 ypos 553 } Output { name Output1 xpos 478 ypos 630 } end_group
Is a MacBeth Colour Rendition Chart the Safest Way to Calibrate a Camera?
www.colour-science.org/posts/the-colorchecker-considered-mostly-harmless/
“Unless you have all the relevant spectral measurements, a colour rendition chart should not be used to perform colour-correction of camera imagery but only for white balancing and relative exposure adjustments.”
“Using a colour rendition chart for colour-correction might dramatically increase error if the scene light source spectrum is different from the illuminant used to compute the colour rendition chart’s reference values.”
“other factors make using a colour rendition chart unsuitable for camera calibration:
– Uncontrolled geometry of the colour rendition chart with the incident illumination and the camera.
– Unknown sample reflectances and ageing as the colour of the samples vary with time.
– Low samples count.
– Camera noise and flare.
– Etc…
“Those issues are well understood in the VFX industry, and when receiving plates, we almost exclusively use colour rendition charts to white balance and perform relative exposure adjustments, i.e. plate neutralisation.”