Exposure Meters and the Cinematographer Study Notes

Author: Gerald Hirschfeld, A.S.C.
Year: 2000

Cinematography involves shooting at 24 frames per second vs. still photography which shoots single frames.
Both art forms share the goal of eliciting an emotional response from viewers.
The cinematographer or director of photography (DP) must make numerous decisions before filming, such as lights used and the exposure meter settings.
Key considerations affecting exposure include:
- Type of film emulsion
- Lab processing methods
- Camera speed
- Shutter angle
- Filters used
- Desired lens stop
- Overall visual “look” for audience emotional reaction
Importance of exposure meter is highlighted as one of the crucial tools for DPs to control image quality and aesthetics.

The cinematographer uses exposure meters to set images according to story requirements.
Cinematic technique varies from still photography, focusing on incident light affecting the subject.
Film specification sheets state necessary light intensity (foot candles) for normal density negatives with standard processing.
Chart reference for various parameters:
- Film emulsion speeds (ISO 25 to 2000).
- T-stops and F-stops (1.4 to 22.6).
- Foot candles (1.25 to 8200).
Example of light requirements:
- For an ISO 500 film at f/4, only 40 foot candles are needed for normal density.
- The DP makes deviations based on desired “look,” confirmed through lab tests.

An incident light meter with a flat disc receptor is leveraged to set the key light at the action’s main position (40 foot candles at action position).
The meter is pointed at the light source, not the camera; hence acceptance of standard gray card reflectivity (18%).
The initial lens stop for this light setting: f/4.
The DP adjusts other lights by eye, read from the one key light.

Background illumination follows key light placement; it is not necessary to measure every light due to the viewing filter aid.
Fill lights are employed to illuminate shadowed areas, enhancing overall luminance.
The DP switches to an incident meter with a hemispherical light integrator, reading all light (key, fill, ambient).
- Direction of the meter during readings: usually between key light and camera for accurate readings.
- Fill light increases lens stop reading typically by a quarter to half a stop dictated by lighting ratios.
Final lens stop can be adjusted post-fill light reading, illustrated through whole setup with an example showing increased intensity from fill lights.

The demand for excellence in feature films requires precise exposure checks, especially in dynamic settings.
A spot meter can efficiently check featured actors' exposures without moving from the camera position, accurately measuring about 1°.
- Consider avoiding readings from overly bright highlights (such as perspiration).
Spot meter readings can be conducted during rehearsals or filming for final exposure adjustments.

Contrary to typical indoor setups, foot candle readings outdoors become challenging due to sun intensity.
- Usage of diffusion materials or cloud cover may adjust sunlight impact.
- The hemisphere dome of the incident meter should not directly face the sun to avoid false readings.
- The DP often shields the dome with their hand against extraneous light exposure during readings.
Landscapes or reflective scenes (like beaches) require compensation adjustments (e.g., one stop for snow, open up for charred fields) for accurate readings.

Advises the use of a spot meter for precise readings of actor’s faces for correct exposure amidst varying surrounding light balances.
Be cautious with extreme lighting contrasts and consider using an 18% gray card for accurate exposure, noting tilt adjustments may impact results.
Highlights importance of knowing the film emulsion range and how to manage exposures based on the selected reading conditions.
Spot meters excel especially in environments where the DP needs to control or gauge light impacts from high or hard-to-reach positions.

Finding reference subjects for spot readings can include green grass, gray roofs, or large rocks displaying mid-tone values instead of solely relying on gray cards.
The significance of learning the subject characteristics that produce readings similar to gray cards through experience is emphasized.
Spot meters prove essential for capturing accurate lighting when shooting from elevated positions or through reflective surfaces (like windshields).

Feature film DPs adapting techniques for videotape productions while possibly adjusting light balances.
Emphasizes the accuracy of lighting and exposure settings over reliance on video monitors which could be improperly calibrated.
- Suggests taking a foot candle reading, adjusting the video camera’s settings for better lighting efficiency post reference checks.

Describes the problems faced when managing multiple meters on film sets needing precise exposure readings under varying circumstances.
Introduces Sekonic model L-508 Cine as a versatile tool, capable of switching between reading modes (foot candle, T/F stops, spot meter).

F-stop: Ratio derived from dividing focal length by lens opening (e.g., 50mm to 25mm opening gives F:2).
T-stop: Reflects actual light transmission capability of a lens, specifically calibrated for cinematography.
Highlights how modern lens advancements impact the reliability of F-stop vs. T-stop measurements for accurate readings.

Career highlights as a cinematographer and his contributions to filmmaking and lighting techniques.
- Extensive experience confirmed through over fifty feature films, teaching roles, and achievements in film-related awards.
- Contributions to cinematic arts illustrated through published materials and workshops focused on lighting and film production.