cinematography
choid
Exposure
FTV 122E: Digital Cinematography Professor Sélène
Exposure
What factors determine Exposure?
Exposure
Factors that determine Exposure
⚫ ISO
⚫ Aperture (Iris) – F-stop
⚫ Shutter Speed (shutter angle)
⚫ Frame Rate
⚫ Light Intensity – the amount of light falling on the scene
The Exposure Triangle
Exposure is controlled through the intersection of
these three elements:
⚫ ISO – the measure of a digital camera sensor’s sensitivity to light
⚫ Shutter Speed / Shutter Angle – the amount of time that the shutter is open
⚫ Aperture – the size of the opening in the lens when a picture is taken * affects Depth of Field
Each of the three aspects of the triangle relate to
light and how it enters and interacts with the
camera.
ISO
ISO or ASA (sensitivity)
⚫ ISO - 100, 200, 400, 800, 1600, 3200, 6400
⚫ Film speed or Digital sensor’s sensitivity to light
⚫ Digital cameras have a “native” ISO – the ISO the manufacturers claim is most optimal for image quality.
⚫ Still, DPs have done tests and sometimes choose to shoot at different ISOs depending on the circumstances
⚫ Higher ISO results in more image noise
High ISO and Digital Noise
High ISO and Digital Noise
Shutter Speed
⚫ What is Shutter Speed?
⚫ Shutter Angle?
⚫ What does shutter speed determine?
Shutter Speed / Shutter Angle
⚫ Shutter speed refers to the amount of time the shutter remains open to capture the image
⚫ Shutter angle is what the the physical rotating shutter in a film camera is set to
⚫ 180-degree shutter represents “normal” blur of motion
Shutter Angle
Shutter Speed / Shutter Angle
Shutter and Motion Blur
Shutter and Motion Blur
Shutter Speed / Shutter Angle
Fast Shutter Speed
⚫ Saving Private Ryan
⚫ Gladiator
⚫ Black Hawk Down
⚫ 28 Days Later
Slow Shutter Speed
⚫ Chungking Express
⚫ Step printing
⚫ Frame Rate
Aperture
Aperture – a light valve that lets in more or less light
Aperture
Aperture
F-stop
F-stops
⚫ f/1, f/1.4, f/2, f/2.8, f/4, f/5.6, f/8, f/11, f/16, f/22, f/32, f/45,f/64, f/90, f/128
⚫ Thinking in “stops”
⚫ Stops is the language DPs and Gaffers speak
⚫ How much “over” or “under” exposed
Double Half Principle
The Exposure Triangle
Exposure is controlled through the intersection of
these three elements:
⚫ ISO – the measure of a digital camera sensor’s sensitivity to light
⚫ Shutter Speed – the amount of time that the shutter is open
⚫ Aperture – the size of the opening in the lens when a picture is taken * affects Depth of Field
Each of the three aspects of the triangle relate to
light and how it enters and interacts with the
camera.
Light Intensity ⚫ Light intensity and fall off
⚫ Inverse Square Law
Inverse Square Law of Illumination
Inverse Square Law of Illumination ⚫ If you double the distance between subject and light source, it illuminates a
surface area four times greater than the one before.
⚫ In general, we therefore multiply the distance with itself in order to calculate the enlargement of that surface area.
⚫ However, a larger surface area leads to a light intensity that is inversely proportional to the square of the distance, since the same amount of light has to be distributed onto a larger surface area respectively.
⚫ Therefore, we see light fall-off, meaning a decrease of light intensity. ⚫ In technical terms the inverse-square law reads as follows: The energy (in our
case: light intensity) at location A (subject area) decreases inversely proportional to the square of A’s distance to the energy source (for example, our flash head).
Inverse Square Law of Illumination
Metering
Light Meter
⚫ How to use a Digital
light meter
⚫ What information is
your light meter giving
you?
Depends on whether it’s
Incident vs. Reflectance
(spot) meter
The Zone System
The Zone System
The Zone System