PPA CPP (Photography) cheat sheet

Exposure value: EV = log2(N²/t) at ISO 100, where N is f-number and t is shutter time in seconds; each full stop doubles or halves light.

Reciprocal rule for handheld: minimum shutter speed ≈ 1/focal length (full-frame equivalent); apply crop factor to the focal length before inverting.

Depth of field increases with smaller aperture (larger f-number), shorter focal length, greater subject distance, and smaller sensor format at equal framing.

Hyperfocal distance H = f²/(N·c) + f, where f is focal length, N is f-number, and c is circle of confusion (0.03 mm full-frame typical); focus at H for DOF from H/2 to infinity.

Crop factor = 43.27 mm / sensor diagonal; it scales focal length and f-number for equivalent field of view and depth of field, not exposure.

Diffraction softening becomes visible around f/11 on full-frame and f/5.6 on Four Thirds; stopping down beyond that trades DOF for resolution.

Guide number GN = f-number × distance (same units); for a flash at ISO 100, distance = GN / f-number, and GN scales by √(ISO/100).

Light loss from extension tubes: effective f-number = f-number × (1 + magnification); a 1:1 macro at f/8 becomes f/16 effective.

Inverse square law: illuminance falls as 1/d²; doubling the distance from a point source reduces light to one quarter (−2 stops).

Soft light requires a source large relative to the subject; moving a softbox closer enlarges its apparent size and softens shadow edges.

Key-to-fill ratio 2:1 gives one stop of fill; 4:1 gives two stops; 8:1 gives three stops of contrast between lit and shadow sides.

Color temperature: tungsten ≈ 3200 K, daylight ≈ 5500 K, shade ≈ 7000–8000 K; mired shift = 1,000,000 / K, and mired differences are additive for filters.

Flash duration t0.5 is the time for output to fall to 50%; t0.1 is the time to fall to 10% and better predicts motion-stopping ability.

Continuous light exposure follows the same EV formula as ambient; flash exposure is controlled by aperture, ISO, and flash power, not shutter speed (below sync speed).

Reflected-light meter calibration: an 18% gray card reads as midgray; a white card should read about +2.3 stops and a black card about −2.3 stops from midgray.

Polarized light is blocked by a polarizing filter rotated 90° to the light's polarization axis; cross-polarization removes specular highlights from glossy surfaces.

Rule of thirds places key elements near intersections of lines dividing the frame into thirds; it is a guideline, not a law.

Leading lines, framing, and figure-ground contrast direct the eye; diagonal lines imply motion and depth more than horizontal or vertical lines.

Gestalt principles: proximity, similarity, continuity, closure, and common fate explain how viewers group elements in a frame.

Visual weight increases with size, contrast, saturation, and isolation; balance a heavy subject with negative space or a smaller counterpoint.

Perspective distortion depends on camera-to-subject distance, not focal length alone; moving closer exaggerates near-far size relationships.

Negative space around a subject increases perceived isolation and emphasis; filling the frame increases intimacy and context.

Color harmony: complementary pairs (opposite on the color wheel) create tension; analogous colors create calm; simultaneous contrast shifts perceived hue and value.

The horizon line should be level unless intentionally tilted; a 1–2° tilt reads as an error, larger tilts read as a stylistic choice.

Bit depth: 8-bit gives 256 levels per channel; 16-bit gives 65,536; 14-bit RAW captures 16,384 levels per channel before demosaicing.

Dynamic range is the ratio of full-well capacity to read noise; a sensor with 14 stops records about 16,384:1.

Color space primaries: sRGB covers roughly 35% of CIE 1931 chromaticity; Adobe RGB covers about 50%; ProPhoto RGB covers about 90% but includes imaginary colors.

Rendering intent: perceptual compresses the full gamut; relative colorimetric preserves in-gamut colors and clips out-of-gamut colors; absolute colorimetric preserves white point.

A camera profile maps device RGB to a connection space (usually XYZ or Lab); DCP profiles include dual-illuminant tables for tungsten and daylight.

Noise: shot noise scales with √(signal); read noise is fixed per pixel; higher ISO amplifies both, reducing dynamic range by roughly one stop per ISO stop.

Demosaicing interpolates missing color channels from a Bayer CFA; false color and moiré are reduced by optical low-pass filters or in-camera processing.

ETTR (expose to the right) maximizes signal-to-noise by placing the brightest important highlight just below clipping, then normalizing in post.

Adjustment layers and smart objects are non-destructive; direct pixel edits (brush, clone) are destructive unless performed on separate layers.

Curves with an S-shape increases midtone contrast; moving the black point right and white point left increases contrast without clipping.

Sharpening has three stages: capture sharpening (corrects demosaic softness), creative sharpening (local emphasis), and output sharpening (compensates for printer or screen).

Luminance masks target brightness ranges; color range masks target hue and saturation; both allow local adjustments without hand-painted masks.

Dodge and burn: dodge lightens (reduces density), burn darkens (adds density); in darkroom terms, more exposure darkens the print, less lightens it.

Retouching ethics: frequency separation separates texture from color; healing brush samples nearby pixels and matches texture and tone automatically.

File formats: PSD/TIFF preserve layers; JPEG is 8-bit lossy; PNG is lossless with alpha; DNG is an open RAW container.

Color grading in video and stills uses lift (shadows), gamma (midtones), and gain (highlights); ASC CDL values are slope, offset, power, and saturation.

PPI = pixels / inches; a 3000 × 2400 px file printed at 300 ppi yields 10 × 8 inches; at 150 ppi it yields 20 × 16 inches.

Halftone screen frequency (lpi) and output resolution: a common rule is 2× the lpi for continuous-tone output; 150 lpi needs about 300 ppi.

ICC profiles describe device gamut and tone response; soft proofing simulates the print profile on screen, and gamut warning shows out-of-gamut colors.

Black point compensation maps source black to destination black, preserving shadow detail when converting between profiles.

Rendering intent for photographic prints is usually relative colorimetric with black point compensation; perceptual is used when many colors are out of gamut.

Paper choice affects gamut and Dmax: glossy papers typically reach higher Dmax and wider gamut than matte papers.

Delivery: sRGB JPEG at 8-bit is the safe web standard; TIFF or PSD with embedded profile is preferred for print; embed profiles to avoid color shifts.

Metadata: IPTC fields carry caption, credit, and rights; EXIF carries camera settings; XMP is the extensible metadata platform used by Adobe applications.

Pricing: cost of doing business (CODB) = annual overhead + desired salary + profit, divided by billable days; day rate = CODB / billable days.

Usage licensing: fees scale with media (print, web, broadcast, outdoor), territory, duration, and exclusivity; buyouts transfer broad rights for a higher fee.

A contract should specify scope, deliverables, revision limits, payment terms, copyright ownership, and cancellation policy.

Model and property releases are required for commercial use of identifiable people and private property; editorial use generally does not require releases.

Invoices should state payment terms (e.g., net 30), late fees, and kill fee; a 50% deposit is common for commissioned work.

Studio lighting ratios: key + fill measured with a meter; a 3:1 ratio means key is about 1.5 stops above fill.

File delivery and archiving: keep RAW originals, deliver processed files, and maintain backups in at least two locations (3-2-1 rule).

Insurance: general liability, equipment, and errors & omissions coverage protect against studio, gear, and professional liability risks.

Evaluate an image by intent, execution, and impact: does the photograph communicate a clear idea, is it technically sound, and does it hold attention?

Histogram reading: a spike at the right edge indicates clipping; a spike at the left indicates blocked shadows; a gap at either end indicates unused tonal range.

Critique vocabulary: value, contrast, saturation, sharpness, framing, moment, gesture, and light quality.

A strong portfolio shows a consistent point of view and editing discipline; 10–20 images often communicate more than 50.

Intentionality distinguishes a mistake from a choice: a tilted horizon, blown highlight, or soft focus can be valid if it serves the concept.

Sequencing: open with a strong image, vary rhythm and scale, and close with a resonant image; group by theme, color, or narrative.

Technical evaluation includes focus placement, motion blur, noise, banding, and color casts; artistic evaluation includes mood, story, and originality.

Reference points: compare against the photographer's own body of work and the genre's conventions, not against a single popular image.

Electrical safety: never touch a strobe's flashtube or capacitors; discharge before servicing; use GFCIs in wet environments.

Battery safety: lithium-ion cells should not be charged unattended, punctured, or stored at extreme temperatures; swelling indicates failure.

Sandbags, safety cables, and weighted stands prevent light falls; never place a stand where it can be tripped over or block an exit.

Ethics: do not misrepresent a photograph as documentary if it has been materially altered; disclose composites and AI-generated elements when relevant.

Copyright: in most jurisdictions, copyright arises on creation and lasts for the author's life plus 70 years; registration strengthens enforcement.

Privacy and publicity: publishing identifiable people for commercial purposes requires consent; editorial use has broader latitude but is not unlimited.

Client confidentiality: do not share unpublished client work without permission; use watermarks and contracts to define usage.

Accessibility and inclusivity: provide alt text, captions, and transcripts for delivered images and video where applicable.