The definition of high key lighting is a style of lighting for film, television, or photography that reduces the lighting ratio in the scene. In the first days of film, this was done to deal with high contrast, but now it's used by filmmakers to adjust the mood and tone of a scene.

Tungsten bulbs are often used to mimic daylight because they produce a warm light. They usually have open-faced light fixtures or Fresnel. They can go up to 200kW and usually have a dimmer switch to help you control direct light. They produce a continuous spectrum of light from near ultraviolet to infrared, producing near-perfect color rendition.

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All the above considered, it's no surprise to see Duplass take to social media with an encouraging statement following the recently announced 2025 Sundance lineup this past Wednesday. Duplass, hot off positive reviews for the recently released The Creep Tapes on Shudder, warmly comforted filmmakers that if you happened to apply to Sundance and weren't selected, hey, that's okay. They curate 15,775. It happens.

A fill light cancels out the shadows created by the key light. A fill light is placed on the opposite of the key light, and usually not as powerful as the key.

Abstract: It is explained what unpolarized light really is, and whether light can be unpolarized when it is (pseudo-)monochromatic.

Clearly, unpolarized light is more difficult to understand than polarized light, essentially because it involves statistical aspects.

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Your film lighting matters in every shot. It can help you set the tone, look professional, and create the atmosphere of your story.

So what's a tungsten light source? Tungsten or Tungsten Halogen lights are incandescent filament bulbs which are common in homes and offices but have been being slowly replaced with longer lasting, more reliable bulbs. What sets these bulbs apart is that they take advantage of what is known as the "halogen cycle." Each bulb has pressurized halogen gas within them. That gas helps redeposit evaporated tungsten metal back onto the filament to shine brightly.

Aside from the camera, lens, and angle, learning how to shape and utilize film lighting is one of the most important lessons and trademarks a filmmaker can have in their toolkit. And that's more than just a 3 point lighting setup. It's a cinematic look.

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Luminous efficacy 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. Watts out versus watts in.

We often consider only plane waves, representing the mathematically simplest field distribution. However, we can also think about a divergent beam, which can be considered to be a linear superposition of plane waves with somewhat different propagation directions. (This idea is the basis of Fourier optics.) Now we might assume that the different plane waves do not only differ in terms of propagation direction, but also a randomly varying polarization directions. Couldn't that lead to unpolarized light even if it is perfectly monochromatic?

We need to think about what it really means for light to be unpolarized. In any moment of time where the electric field at a certain position in space doesn't happen to be zero, the electric field vector points in a certain direction. In that sense, light is always polarized! However, there are situations where the orientation of the electric field vector fluctuates such that when averaging over a certain time interval we do not find any preferred field orientation – the light is then indeed unpolarized.

But how can you know if you’re hitting all the basics without a comprehensive checklist? We put our heads together and came up with this list that should help any filmmaker master the basics and take on the industry.

We all know rejection sucks, but don't sweat it. Be proud of your project no matter what. And watch Mark Duplass's full snippet of encouraging wisdom below.

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Now it is clear that such fluctuations, which are indispensable for light to be unpolarized, cannot occur for strictly monochromatic light because there we cannot have any fluctuations – only a perfectly periodic oscillation of electrical and magnetic field. In conclusion, strictly monochromatic light cannot be unpolarized.

All of them. Each light we covered has a specific purpose. So it really depends what you're trying to do on set, hat you have access to, and the nature of the scene and story.

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.

There are many types of film lights, but we want to categorize light fixtures first to give you the basics before it gets complicated.

HMI stands for Hydrargyrum medium-arc iodide. So, maybe stick with saying HMI light. Much easier. HMI lights are a metal-halide gas discharge medium arc-length lamp. Yup, we are getting super technical. HMI lamps are capable of between 85 and 108 lumens per watt, up to four times that of conventional incandescent lamps. They're able to produce that high of an output thanks to a chemical reaction between mercury and electricity in the bulb.

Note that we then still have a strong correlation of field vector orientations across the beam profile – in contrast to a beam of sunlight, for example.

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.

A Fresnel lens is a type of lens that is divided into repeating concentric circles. This results in a thinner lens than a conventional lens of similar power. This lens provides an even light and allows the beam to be varied from flood to spot. It does this by changing the distance between the lamp/reflector unit and the lens.

Mark Duplass has always been a filmmaker's filmmaker. He famously delivered his "The Cavalry is Not Coming" speech at SXSW as a call to action for independent filmmakers to stop waiting and start shooting. Duplass also historically creates and works on small-budget indie projects, including being a key member of the lo-fi, bare-bones mumblecore movement. He's also a charismatic actor who brings a relatable ethos to every role he plays—not to mention seems like an overall cool dude.

A practical light is a source of light that comes from an object within the scene being filmed. To cheat brighter or dimmer, existing bulbs are swapped out for those of different wattage or color temperature.

We can also consider a situation where the electric field vector systematically rotates around the propagation axis. If the rotation frequency equals the optical frequency, we then have circularly (or elliptically) polarized light, for lower rotation frequencies linearly polarized light with a rotating polarization direction – in any case, no unpolarized light! So for unpolarized light we indeed need random fluctuations, not a systematic evolution of field vector direction.

At a first glance, one may think that the optical bandwidth of light and its polarization are totally unrelated things, and many people may answer the question “Can monochromatic light be unpolarized” with “Sure, why not?”. However, it actually turns out to be an interesting and non-trivial question.

The definition of low key lighting is a filmic lighting style that uses a hard source to encase your scene in shadow. Low key lighting wants contrast and blackness.

Okay, now we're getting into the fun stuff. Light sources change depending on the kinds of bulbs you use. The build will affect the color temperature and bulb strength can change the CRI as well. So let's dive deep.

1,700 K: Match flame1,850 K: Candle flame, sunset/sunrise2,700–3,300 K: Incandescent lamps4,100–4,150 K: Moonlight5,000 K: Horizon daylight5,500–6,000 K: Vertical daylight6,500 K: Daylight, overcast15,000–27,000 K Clear blue poleward sky

Let's talk about film lighting. It's more than just three-point lighting and motivated setups. We want to go overlighting placement and schemes to help you really emphasize what you want on screen.

We've deconstructed lighting on No Film School before, but today we want to aggregate all the ideas and techniques behind picking a lighting scheme for your film. These are video lighting setups and film lighting setups that are crucial to storytelling.

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. Yeah, that's a mouthful. You'll understand color temperature better if you've ever changed a light bulb at home and noticed that it doesn't match the other bulbs in your fixture. Light can be warm (yellow/orange) or cool (blue). Color temperature can even affect the tone of your story. The best lighting misses both cool and warm to create an environment and to get the color you want out of an object or subject.

A fluorescent light contains low-pressure mercury vapor bouncing around to produce ultraviolet light. Fluorescent lights are more efficient than incandescent light. They are capable of generating up to 100 lumens per watt, similar to the output of HMI. So what's that mean? It means that the spectrum of light emitted can achieve a CRI up to 99. The color temperature of a fluorescent can vary also from 2700K to 6500K.

When inspecting the electric field at any fixed point in the beam profile, the answer is no; the arguments presented above fully apply. However, we may get unpolarized light in the weak sense that the transmission of optical power of the complete beam through a polarizer will be independent of the orientation of that polarizer. That is not truly unpolarized light, however: the transmission trough a polarizer will exhibit a fixed spatial pattern.

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.

Up-to-date technical know-how is the key to success in photonics. RP Photonics offers high quality training courses at your location:

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A backlight hits an actor or object from behind. It is placed higher than the object it is lighting. Backlights are used to separate an object or an actor from a background. They give more shape and depth. Backlights help the frame feel three-dimensional.

In practice, however, we are often dealing with quasi-monochromatic light. That means that the optical bandwidth is so small that in some respects it is equivalent to a zero bandwidth. For example, we could not resolve the optical spectrum with any ordinary optical spectrum analyzer. As a numerical example, we may have a bandwidth of 1 MHz, which is orders of magnitude less than the mean optical frequency, which is hundreds of terahertz for visible light. That bandwidth implies that we can have significant changes of field vector direction within one microsecond (the inverse of the bandwidth). When averaging over 1 ms, for example, we may find the light to be completely unpolarized. In such a situation, one could say that although the light is quasi-monochromatic in some sense (e.g. for our spectrum analyzer), it is sufficiently non-monochromatic to be unpolarized.

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Have you ever been overwhelmed at the possibility of every camera angle, framing, and shot type available as a filmmaker? Us too. So we provided a cheat sheet with definitions for you! There are so many camera movements and camera angles; it can be hard to keep track. To make film and television like the masters, you need to practice and learn the various camera movements, angles, shots, and tools.

An open-faced lighting fixture creates hard light that casts hard shadows on the subject. It provides nothing to filter the subject from the bulb's light.

There are devices (called depolarizers or polarization scramblers) which can be used for converting polarized light into unpolarized light. Our discussion makes clear that those need to introduce some fluctuating time dependence, if we need unpolarized light at every location across the beam profile. For example, one may use a Pockels cell which is driven with a randomly fluctuating electric signal (or a combination of multiple cells). With such kind of devices, one can for example depolarize a linearly polarized laser beam. The shorter the measurement time over which the light needs to be unpolarized, the larger must be the bandwidth of the applied noise modulation.

This article is a posting of the Photonics Spotlight, authored by Dr. Rüdiger Paschotta. You may link to this page and cite it, because its location is permanent. See also the RP Photonics Encyclopedia.

CRI stands for Color Rendering Index. The Color Rendering Index 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.

A key light is the primary light source of the scene. It is the most intense and direct light source. Generally, the key light will illuminate the form of the subject or actor.

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.

LED stands for light emitting diode. LED lights are solid-state semiconductor device. LED’s are extremely efficient. They're truly the lights of the future, mostly because we keep inventing new ways to use them. Right now they are limited in overall light output when compared to any of the other light sources. But things can change fast. LED lights can reflect daylight and many have a variable color temperature. So you can seamlessly switch color temperature as needed. The CRI rating of LED lighting can be over 90.