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840 terms · page 28 of 35


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All A B C D E F G H I J K L M N O P Q R S T U V W X Y Z 0–9
Exposure & Metering

Reciprocal Rule

A handholding guideline stating that the slowest safe shutter speed is roughly one over the focal length in use.

t ≤ 1 / (focal length × crop factor) seconds
Film, Darkroom & Historic Processes

Reciprocity Failure

The breakdown of the reciprocity law at very long or very short exposures, where film needs more light than calculation predicts.

t_corrected = t^p seconds
Exposure & Metering

Reciprocity Law

The principle that exposure depends only on the product of light intensity and time, so halving one and doubling the other leaves the…

H = E × t lux-seconds (lx·s)
Lighting & Flash

Recycle Time

The interval a flash needs to recharge its capacitor to full power after firing.

seconds
Exposure & Metering

Reflected-light Metering

Measuring the light bouncing off a subject toward the camera, which is what every built-in camera meter does.

EV
Motion, Video & Creative Techniques

Reflection Photography

Using reflective surfaces — water, glass, metal, screens — as a compositional device rather than a nuisance.

Lighting & Flash

Reflector

A panel that bounces existing light back into the shadows, adding fill without a second light source.

stops
Colour & Colour Management

Relative Colorimetric Intent

A conversion strategy that reproduces in-gamut colours exactly and clips out-of-gamut ones to the nearest reproducible value.

Focus & Depth of Field

Release Priority

A setting that fires the shutter whenever the button is pressed, regardless of whether focus has been confirmed.

Lighting & Flash

Rembrandt Lighting

A portrait pattern in which a small triangle of light appears on the shadowed cheek, below the eye.

Colour & Colour Management

Rendering Intent

The strategy chosen for handling colours that fall outside the destination gamut during a colour space conversion.

Film, Darkroom & Historic Processes

Resin-coated Paper

Photographic paper sealed between thin polyethylene layers so chemistry cannot penetrate the base.

g/m²
Optics, Lenses & Filters

Resolving Power

The finest detail a lens or film can distinguish, traditionally expressed in line pairs per millimetre.

lp/mm
Optics, Lenses & Filters

Retrofocus Design

A wide-angle design with a negative front group that places the rear element further from the sensor than the focal length would allow.

Exposure & Metering

RGB Histogram

Three separate histograms, one per colour channel, revealing clipping that a combined luminance histogram would hide.

Lighting & Flash

Rim Light

A light placed behind and to one side of the subject that draws a bright edge along its outline, separating it from the background.

f-stops (EV)
Lighting & Flash

Ring Flash

A flash tube arranged in a circle around the lens, producing nearly shadowless frontal light.

GN (guide number)
Sensors & Digital Capture

Rolling Shutter Artefact

Distortion caused by a sensor being read out progressively, so different parts of the frame record at slightly different times.

ms
Files, Metadata & Workflow

Round-trip Editing

Sending an image from a catalogue to an external editor and returning the result automatically to the same collection.

Composition & Visual Design

Rule of Odds

The observation that an odd number of subjects in a frame usually reads as more settled than an even number.

count
Composition & Visual Design

Rule of Space

The guideline that a subject which is moving or looking in a direction should have space in front of it within the frame.

Composition & Visual Design

Rule of Thirds

A guideline that divides the frame into nine equal parts and suggests placing key elements along those lines or at their intersections.

Frame ÷ 3 horizontally and vertically
Composition & Visual Design

S-curve

A gently reversing curve within a scene that carries the eye through the frame in a sinuous path.

Film, Darkroom & Historic Processes

Safelight

A darkroom lamp emitting only wavelengths to which the material in use is insensitive.

nm