PPA CPP (Photography) key terms

The largest blur spot on the sensor that a viewer will still perceive as a sharp point at a given viewing size and distance. It sets the depth-of-field calculation limits.

The closest focus distance at which everything from half that distance to infinity appears acceptably sharp for a chosen focal length, aperture, and circle of confusion.

Illuminance from a point source falls off with the square of the distance: doubling the distance to a light reduces its intensity to one quarter. It governs falloff in lighting setups.

The gradual decrease in light intensity across a scene or toward the edges of a frame, caused by distance from the source, modifier shape, or lens vignetting.

A flash rating expressing reach: the aperture needed equals the guide number divided by the flash-to-subject distance. It scales with ISO and is usually quoted in meters or feet.

The fastest shutter speed at which the entire sensor is briefly uncovered while the flash fires. Exceeding it produces a partially dark frame unless high-speed sync is used.

A mode in which the flash pulses rapidly to stay lit throughout a fast shutter's travel, allowing flash use above the camera's normal sync speed at reduced output.

A description of a light source's warm or cool appearance, expressed in kelvin, by comparing it to a black body heated to that temperature. Lower values look warmer.

A 0-100 score for how faithfully a light source reveals colors compared with a reference illuminant. High scores suit color-critical photography; the metric has known limitations with LEDs.

The relative brightness of the main light versus the fill light, often stated as a ratio such as 4:1. It controls how pronounced shadows and modeling appear on a subject.

A framing heuristic that places important elements near lines dividing the frame into thirds, or at their intersections. It is a starting point, not a rule that guarantees a strong image.

Linear elements in a scene, such as roads, edges, or shadows, that guide the viewer's eye toward a subject or through the frame to create depth and flow.

Empty or low-detail areas surrounding a subject that give it room to breathe and strengthen emphasis. It is an active compositional choice, not wasted frame area.

The visual separation between a subject and its surroundings. Strong separation through tone, color, focus, or lighting makes the subject read clearly and quickly.

Perceptual principles, including proximity, similarity, and closure, by which viewers organize separate elements into unified shapes or patterns. They explain why compositions read as coherent.

The apparent pull an element exerts on attention, influenced by size, contrast, color saturation, sharpness, and position. Balancing weights creates stable or intentionally tense compositions.

Darkening toward the corners of an image, caused by lens design, filters, or deliberate post-production. Natural vignetting is often considered pleasing; heavy mechanical vignetting is a defect.

A single number encoding a combination of aperture and shutter speed at a stated ISO, so equivalent exposures share one value. Each step of one represents a doubling or halving of light.

The interplay of aperture, shutter speed, and ISO, where changing one to alter brightness requires compensating with another, with side effects on depth of field, motion, and noise.

A logarithmic unit for halving or doubling light. One stop equals a factor of two in exposure, and standard aperture, shutter, and ISO scales advance in one-stop steps.

The ratio of focal length to effective aperture diameter, written as f/2.8 or f/8. Smaller numbers mean larger openings and less depth of field; each full step halves the light.

The zone in front of and behind the focused distance that appears acceptably sharp. It grows with smaller apertures, shorter focal lengths, and greater subject distance.

The point at which stopping down further softens the image because light bending at the aperture edge spreads across pixels. It arrives sooner on high-density sensors.

Color fringing along high-contrast edges caused by a lens focusing different wavelengths at slightly different planes or magnifications. Lateral and longitudinal forms behave differently.

The number of bits used to store each color channel's value. Eight bits per channel gives 256 levels; 16 bits gives far more headroom for editing gradients without banding.

A graph of pixel counts by brightness or color value. It shows tonal distribution and clipping but says nothing about whether the image is well composed or correctly exposed artistically.

Loss of detail when pixel values exceed the maximum or fall below the minimum recordable level, appearing as solid white or black. Clipped highlights cannot be recovered in post.

Unprocessed sensor data saved with minimal in-camera adjustment, retaining maximum tonal and color latitude. It requires conversion software and is not a directly printable final file.

The range of colors a device, working space, or output can reproduce. Converting to a smaller gamut can shift saturated colors unless rendering intent is chosen carefully.

A file describing how a device's color values map to a standard color space. Profiles let editing software translate colors between camera, monitor, and printer accurately.

The rule used when converting between color gamuts, such as perceptual or relative colorimetric. It determines whether out-of-gamut colors are compressed smoothly or clipped precisely.

Simulating a printer and paper's color and contrast on a calibrated monitor before printing, so adjustments can be made without wasting materials.

Adjusting color values so that neutral objects render without a color cast under a given light source. It can be set in camera or corrected later from raw data.

A selection built from an image's brightness values, letting edits target highlights or shadows selectively. It is a core technique for local contrast and exposure adjustments.

A bright or dark outline artifact around edges caused by excessive or large-radius sharpening. It is a common sign of over-processing in output files.

Sharpening tuned to the final medium, viewing distance, and resolution, applied after resizing. Screen, inkjet, and press outputs each need different amounts.

The amount of detail a capture, file, or output device can represent, expressed in pixels or pixels per inch. PPI describes file density; DPI describes printer dot placement.

A signed agreement from a recognizable person permitting commercial use of their likeness. It protects the photographer and client from claims over advertising or stock usage.

Permission from an owner of private property, such as a building or artwork, to use its image commercially. It is distinct from a model release for people.

Exclusive legal rights over an original image, including reproduction and licensing, arising automatically on creation in many jurisdictions. Ownership can be transferred only in writing.

A legal arrangement in which the commissioning party owns the copyright from the outset, typically requiring a written agreement. Without it, the creator usually retains ownership.

A studio's documented rules for assigning, converting, and embedding profiles across capture, editing, and delivery, ensuring consistent color between collaborators and clients.

Shooting with the camera connected to a computer so images appear immediately on a larger screen. It aids client review, focus checking, and consistent lighting control.

The period shortly after sunrise or before sunset when low-angle sunlight is warm and soft, producing long shadows and flattering directional light.

The brightness difference between the lightest and darkest tones in a scene or display. It shapes perceived drama and the legibility of shadow and highlight detail.

The instant when subject, gesture, and composition briefly align into a coherent whole. Recognizing it requires anticipation and readiness rather than luck alone.

A document listing hazards, handling, and first-aid measures for a chemical product. Photographers should keep one for each solvent, ink, or darkroom chemistry on site.

Following workplace rules for storing, labeling, ventilating, and disposing of photographic chemicals and waste. It protects staff, clients, and the business from liability.

Agreement given after a subject understands how an image will be used, where it will appear, and for how long. It underpins ethical documentary and editorial practice.