Inverse Square Law of Lighting

What is the inverse square law of light? How does this affect you when you are lighting a scene?  What do you need to keep in mind?

    The inverse square law of light is used to calculate the fall-off of a light source as you increase/decrease the distance from the subject. Regarding light fall-off, a light source emits a set number of rays on the subject. When it's closer, the rays are more condensed and make the light appear brighter and stronger. When the light source is further, it spreads those rays across more space, creating a sort of feathered look and decreasing the amount of light that is actually hitting the subject. The exact formula for the inverse square law of light when increasing the distance is i=1/d^(2), with "i" being intensity and "d" being distance. What this formula tells you is how much the intensity decreases based on the distance. For instance, when you increase the distance of a light from the subject by 2 times, the intensity is 1/4 the amount of light. When you want to move the light closer, the formula is i=d^(2). This affects me when I'm lighting a scene because I may need to adjust my lighting either to get a more desired look or to fix issues such as unwanted lights overpowering the lights that I do want. The main thing that I need to keep in mind is that the closer a light, the more intense, and the further the light, the less intense.

Reviewing 3-Point Lighting

What are the three different parts of 3-point lighting? What are three tips that this presenter makes that are different than what you have been taught so far in this class? How can you put this knowledge into use in your future videos?

    The three different parts of 3-point lighting that the video goes over are the key light, motivated light, and back light. The key light is the primary light source that is responsible for exposure and is the first point of 3-point lighting. The next point is motivated light, which should appear to come from some kind of object within the scene: a lamp, a window, a candle, etc. The back light should be the brightest light source and is used to separate the subject from the background. This can come in the form of a rim light, which outlines the subject or a hair light if it highlights just the hair. Three tips that this presenter makes which differ from what I have been taught in class are the purpose of a fill light, backlight, and the emphasis on the sun.

    In this video, he says that good cinematographers don't use a dedicated light as a fill light, but rather use motivated light as the fill light. This differs from what we've learned as we learned that the fill light or the reflector is one of the points, whereas the presenter says that motivated light is a point instead. Regarding back lighting, we've learned to use a back light just to highlight the hair, but he also talked about how it can be used to outline the subject. A major point within his video is the importance of the sun when it comes to lighting. He really emphasizes understanding the way our world is naturally lit by the sun, which we hadn't learned in class.

    I can put this knowledge to use in my future videos by considering 3-point lighting and remembering the purpose of the different points, which can massively improve the quality and artistic appeal of my images.

Using a Waveform for Exposure

What is the IRE scale?  What does it mean on the waveform? What is crushing and clipping?  What does it tell you when you see it happening on the waveform? Why is the waveform monitor so important to the digital cinematographer?

    The IRE scale is the measurement of exposure from 0% to 100%, with 0 being black and 100 being white. On the waveform, it means that the higher the data is, the higher that the exposure is. Crushing is when data that is below 0% is cut off and clipping is when data above 100% is cut off. When they happen on the waveform, it tells you that they are at the absolute max or minimum for what is broadcast legal, causing the image to lose discernible detail in those extremes. The waveform monitor is so important to the digital cinematography because image monitors are less trustworthy because of a variety of outside factors that can affect the way the image look without actually changing the image that's shot, which can create issues and lead to mistakes. However, a waveform monitor shows the actual data, which then allows them to know what actually needs to be done for their desired image and exposure.

Using Zebras for Exposure

What are zebra stripes?  What are they used for? What do the zebra stripes tell you? What a practical way to use these while shooting with a video camera?

    Zebra stripes are... They are used for... Zebra stripes tell you... A practical way to use these while shooting are...

Reviewing Gain

What does the ISO/Gain sensitivity of a camera mean? Why would you want to increase the ISO/Gain of the camera? What happens when you increase the ISO/Gain on a camera?  What are the problems that come into play?

    ISO refers to the sensitivity of the sensor that's receiving the light for your camera. You would want to increase the ISO/Gain when you're filming in low light and need the sensor to be more sensitive to the light, increasing the exposure. The more you increase the ISO/Gain on the camera, the brighter the image will appear. That being said, the increase in sensitivity makes the camera pick up on more digital noise, thus adding this noise into the image. Thus, it is ideal to shoot with low to no gain to prevent this digital noise and try to use other methods to brighten the image through lighting or other settings that impact exposure.

Getting the Correct Exposure

What is a gray card used for?  What does it help represent? What is a waveform monitor used for?  How should you use it? What is false color?  How can it be used to determine exposure?

    The gray card is used for... It helps represent... A waveform monitor is used for... You should use it by... False color is... It can be used to determine exposure as...

F-Stops Explained

What is the difference between the aperture and the iris?  In your own words, what is an F-stop?  What is the difference between each stop?  Explain in detail.

    The difference between the aperture and the iris is that the iris is a circular disc that opens and close depending on how much light you want the camera to see and the aperture is the name of the hole on the iris that lets light in. An F-stop is the unit of measurement that dictates how wide the aperture is and thus how much light goes into the lens. The difference between each stop is that each point either doubles or halves the area of the aperture depending on whether you increase or decrease the F-stop.