Photometry, Digital Asset Management, and Exposure Metering

Vocabulary flashcards covering photometry principles, digital asset management with Lightroom Classic, and exposure meter operations.

Inverse-Square Law

A photometric principle stating that illuminance from a point source varies inversely with the square of the distance ($\text{Illuminance} \propto \frac{1}{\text{distance}^2}$).

Candle Power

A measurement of illuminance from a wax candle point light source, nominally producing $1\,\text{lux}$ at a distance of $1\,\text{meter}$.

Mired Value

A unit of color temperature measurement calculated as $\frac{1,000,000}{\text{Color Temperature in Kelvin}}$ ($\text{Mired} = \frac{10^6}{\text{CCT}}$).

Mired Shift

The calculated difference in Mired values between two light source temperatures or settings ($\text{Mired Shift} = T_2 - T_1$).

Color Temperature Scale

A scale measured in Kelvin ($\text{K}$) rating the warmth or coolness of light, where lower values represent warmer, reddish light and higher values represent cooler, bluish light.

Chromatic Adaptation

A characteristic of human vision where the eyes and brain adjust to the color of surrounding light, causing observers to perceive light sources as neutral even when actual color temperatures vary.

Color Rendering Index (CRI)

A quantitative metric of a light source's ability to accurately reveal object colors compared to natural light; sources with continuous spectra have high CRI, while discontinuous sources have lower CRI.

Catalog Software

An essential component of Digital Asset Management (DAM) that manages image collections, creates thumbnails, captures metadata, enables offline browsing, and supports collection recovery.

Smart Previews

Image previews generated in Lightroom that allow full image browsing and parametric editing even when the original source files or hard drives are disconnected.

Find Missing Folder

A Lightroom command accessed by right-clicking or Control-clicking a folder marked with a question mark icon to navigate the file system and re-link the catalog to its new disk location.

Parametric Image Editing (PIE)

A non-destructive editing workflow used by Lightroom that creates a set of parameter instructions applied dynamically to an image without modifying the original pixel data.

Basic Panel

A key panel in Lightroom Classic's Develop module containing tools for adjusting a photo's white balance, color saturation, and tonal scale.

Preset

A saved group of settings in Lightroom (such as export parameters or development adjustments) that can be repeatedly applied to other photos to streamline workflow.

Scale Linearity

The property of an exposure meter where its measured output values change in direct proportional increments relative to changes in light attenuation or neutral density.

Transmittance

The fraction or percentage of incident light intensity that successfully passes through an optical filter or medium.

Opacity

The reciprocal of transmittance ($\text{Opacity} = \frac{1}{\text{Transmittance}}$), measuring a material's resistance to light transmission.

Optical Density

The logarithmic measurement of opacity ($\text{Density} = \log_{10}(\text{Opacity})$), commonly used to quantify light reduction by optical filters.

Reflected-type Reading

An exposure measurement taken by aiming the meter from the camera position toward the subject to measure light reflected off the subject's surface.

Incident-type Reading

An exposure measurement taken at the subject position pointing toward the camera to measure the light falling directly on the subject.

Spot Metering

An exposure reading mode targeting a narrow area of a scene; metering off a surface that is not $18\%$ gray will adjust exposure to render that specific tone as middle gray.

ColorChecker Passport

A physical calibration target containing standardized color and grayscale patches used for white balance correction and camera color profiling.