Lenses, Focus, and Exposure#
Lens terms are most useful when they describe a visible result. Focal length changes field of view when camera position is fixed; the camera-to-subject position creates the familiar perspective change. In prompts, combine lens class, focus behavior, and exposure effect only when they serve the composition.
Focal-length vocabulary#
Full-frame-equivalent values below are practical visual shorthand; actual field of view depends on sensor or film format.
| Term |
Approximate range |
Visible character |
Prompt cue |
| Circular fisheye |
4–8mm |
Circular image, 180° or wider coverage, extreme curved projection. |
circular fisheye view |
| Full-frame fisheye |
8–15mm |
Frame-filling ultrawide with strongly bowed straight lines. |
diagonal fisheye perspective |
| Extreme ultra-wide |
10–14mm |
Immense field, dramatic near-far scale, stretched edges. |
12mm rectilinear interior |
| Ultra-wide |
15–20mm |
Expansive architecture and landscape, strong foreground emphasis. |
18mm ultra-wide view |
| Wide angle |
21–35mm |
Environmental context and energetic spatial depth. |
28mm documentary perspective |
| Normal / standard |
40–58mm |
Natural-looking field with moderate spatial relationships. |
50mm natural perspective |
| Short telephoto / portrait |
70–105mm |
Narrower view, flattering working distance, background separation. |
85mm portrait lens |
| Medium telephoto |
105–200mm |
Isolates subjects and layers backgrounds tightly. |
135mm compressed perspective |
| Super-telephoto |
300–800mm+ |
Very narrow field, distant subjects, pronounced atmospheric layers. |
600mm wildlife photograph |
| Macro lens |
Commonly 60–200mm |
Close focus and high reproduction ratio, not a perspective by itself. |
1:1 macro photograph |
| Tilt-shift lens |
Commonly 17–90mm |
Movements control convergence and focus-plane orientation. |
24mm tilt-shift architecture |
| Probe lens |
Long narrow macro optic |
Ground-level, inside-object, or miniature tracking viewpoint. |
probe-lens macro view through ingredients |
Perspective and lens rendering#
| Term |
Effect |
Clarification |
| Exaggerated near-far scale |
Nearby objects appear very large relative to distant ones. |
Usually created by close camera placement with a wide lens. |
| Telephoto compression |
Background layers appear tightly stacked. |
Caused by distant camera placement and narrow framing, not optical flattening alone. |
| Edge stretching |
Faces or circular objects elongate near wide-frame edges. |
Keep important subjects near center to avoid it. |
| Rectilinear rendering |
Straight scene lines remain straight. |
Ultra-wide rectilinear lenses still stretch edges. |
| Curvilinear rendering |
Straight lines bow outward or around the center. |
Typical of fisheye projection. |
| Barrel distortion |
Lines bow outward from center. |
Common stylized wide-lens artifact. |
| Pincushion distortion |
Lines bend inward toward center. |
More associated with some telephoto/zoom designs. |
| Mustache distortion |
Complex wave-like line bending. |
Usually an unwanted technical artifact. |
| Corner falloff / vignetting |
Corners darken or lose brightness. |
Can frame a subject; distinguish optical from added vignette. |
| Cat's-eye bokeh |
Out-of-focus highlights become clipped ovals near frame edges. |
Adds realistic fast-lens character. |
| Swirly bokeh |
Background blur curves around center. |
Strong vintage-lens signature; can distract. |
| Soap-bubble bokeh |
Highlights have bright rims and hollow centers. |
Distinctive vintage optical rendering. |
| Anamorphic rendering |
Wide image, oval bokeh, horizontal flare, edge distortion. |
State only desired traits instead of using anamorphic as generic cinema shorthand. |
Shot scale and framing#
| Term |
Typical framing |
Common purpose |
| Extreme close-up (ECU) |
Eye, lips, watch mechanism, tiny surface detail. |
Intensity, evidence, texture. |
| Close-up (CU) |
Face or similarly sized object fills frame. |
Emotion and detail. |
| Medium close-up (MCU) |
Head and shoulders or chest-up. |
Interviews and intimate portraits. |
| Medium shot (MS) |
Roughly waist-up. |
Gesture plus expression. |
| Cowboy / American shot |
Mid-thigh upward. |
Hands, holsters, fashion, conversational action. |
| Medium full shot |
Knees upward. |
Body language with facial readability. |
| Full shot |
Entire body with modest surrounding space. |
Pose and wardrobe. |
| Wide shot |
Subject small enough to establish environment. |
Spatial relationships and scale. |
| Extreme wide shot (EWS) |
Environment dominates; person may be tiny. |
Geography, isolation, spectacle. |
| Establishing shot |
Broad view introducing location and layout. |
Narrative orientation. |
| Detail / insert shot |
Isolated story-relevant object or action. |
Continuity and emphasis. |
Depth of field#
| Term |
What remains sharp |
Prompt cue |
| Razor-thin focus |
A very narrow plane, perhaps only an iris or object edge. |
razor-thin macro depth of field |
| Shallow depth of field |
Subject plane sharp, foreground and background soft. |
shallow depth of field, face in focus |
| Moderate depth of field |
Subject and immediate context readable, distant background softened. |
moderate depth of field |
| Deep focus |
Foreground, middle ground, and background remain legible. |
deep-focus scene |
| Hyperfocal focus |
Focus placement maximizes acceptable near-to-infinity sharpness. |
hyperfocal landscape sharpness |
| Selective focus |
One chosen feature receives focus emphasis. |
selective focus on the red button |
| Focus falloff |
Transition from sharp to blurred planes. |
gentle natural focus falloff |
| Focus wedge |
Tilted plane of sharpness created by lens movement. |
tilted focus plane across the table |
| Miniature focus effect |
Narrow band of sharpness makes a large scene resemble a model. |
tilt-shift miniature effect |
Avoid asking for f/1.2 shallow depth of field when every object at several distances must be perfectly sharp. Describe which planes should be readable.
Focus placement and behavior#
- Eye focus: nearest eye is crisply focused; reliable portrait instruction.
- Face-detection focus: all main facial features should be acceptably sharp.
- Foreground focus: nearest object is sharp while subject behind softens.
- Background focus: foreground becomes an intentional blurred frame.
- Rack focus: focus shifts between planes over time; in a still, specify the final focused plane.
- Split diopter: near and far subjects are sharp while the middle may blur, often with a visible seam.
- Zone focus: predetermined distance range remains sharp, common in street photography.
- Soft focus: deliberate glow and reduced microcontrast while edges remain recognizable.
- Defocus: entire scene intentionally out of focus; useful for abstract light fields.
- Motion-softened detail: blur from movement, not missed focus.
- Tack sharp: crisp focus at the chosen plane; do not apply indiscriminately to all depths.
Bokeh vocabulary#
| Term |
Appearance |
Useful context |
| Creamy bokeh |
Smooth, low-structure blur with gentle highlight edges. |
Portraits and products. |
| Busy / nervous bokeh |
Double edges and textured blur draw attention. |
Intentional gritty or vintage look. |
| Circular bokeh |
Round out-of-focus point lights. |
Night lights, foliage highlights. |
| Polygonal bokeh |
Aperture-blade shapes visible in highlights. |
Stopped-down or vintage optics. |
| Oval bokeh |
Vertically stretched highlights. |
Anamorphic-inspired imagery. |
| Donut bokeh |
Ring-shaped highlights from mirror lenses. |
Distinctive retro telephoto look. |
| Bubble bokeh |
Bright-edged circular highlights. |
Dreamy but visually active backgrounds. |
| Bokeh balls |
Large isolated blurred light circles. |
Festive or urban night backgrounds. |
| Foreground bokeh |
Soft objects or lights overlap frame edges. |
Adds depth and concealment. |
Aperture language#
| Aperture idea |
Typical visible result |
Prompt wording |
| Wide open / fast aperture |
Shallow focus, strong separation, round highlights, possible softness. |
wide-open lens, shallow focus |
| Moderate aperture |
Balanced subject sharpness and separation. |
moderate aperture, context still readable |
| Stopped down |
Deeper focus, sharper starbursts, possible diffraction at extremes. |
stopped-down architectural photograph |
| Sunstar / diffraction star |
Point source forms rays based on aperture blades. |
crisp 14-point sunstar |
F-number syntax can be useful (f/1.4, f/8, f/16), but visible consequences are usually more important than a nominal value.
Shutter and motion rendering#
| Term |
Motion treatment |
Prompt cue |
| Frozen motion |
Fast exposure arrests droplets, fabric, or athletes. |
1/2000-second frozen motion |
| Subtle motion blur |
Moving extremities or background show a short directional trail. |
slight natural motion blur |
| Long exposure |
Moving water, traffic, clouds, or people smear over time. |
30-second long exposure |
| Light trails |
Moving lights draw continuous lines. |
red and white traffic light trails |
| Silky water |
Water averages into smooth ribbons or mist. |
long-exposure silky waterfall |
| Panning shot |
Camera follows subject; subject relatively sharp, background streaked laterally. |
panning photograph of cyclist |
| Rear-curtain flash |
Sharp flash endpoint with motion trail behind it. |
rear-curtain flash motion trail |
| Front-curtain flash |
Trail may appear ahead of frozen subject, less natural directionally. |
Specify only when desired. |
| Zoom burst |
Focal length changes during exposure, making radial streaks. |
in-camera zoom-burst effect |
| Intentional camera movement (ICM) |
Camera motion creates abstract vertical, horizontal, or circular smears. |
vertical ICM forest photograph |
| Stroboscopic sequence |
Repeated flash records multiple phases of motion. |
stroboscopic dancer sequence |
Exposure and dynamic range#
- Correct / balanced exposure: important highlights and shadows retain natural detail.
- Underexposed: overall dark capture; can be moody but may bury information.
- Overexposed: overall bright capture; may look airy or wash out detail.
- Expose for highlights: protect bright sky, flame, white clothing, or reflective product.
- Expose for shadows: lift darker areas, potentially allowing highlight clipping.
- High-key exposure: bright tonal distribution with intentional pale background and soft shadows.
- Low-key exposure: dark tonal distribution with selective illuminated areas.
- High dynamic range: broad highlight-to-shadow detail; request
natural to avoid exaggerated tone mapping.
- Bracketing / exposure blend: several exposures combined for architecture or interiors.
- Silhouette exposure: meter for bright background so foreground subject goes dark.
- ETTR-like clean shadows: bright capture preserving data without clipping; primarily technical rather than stylistic.
Optical and capture artifacts#
| Artifact |
Appearance |
Use carefully |
| Lens flare |
Ghost shapes, streaks, or veiling from bright off-axis sources. |
Specify color, strength, and source. |
| Anamorphic flare |
Long horizontal streak across bright lights. |
Easy to overproduce. |
| Chromatic aberration |
Colored fringes at contrast edges, especially frame corners. |
Suggests imperfect or vintage optics. |
| Coma |
Corner point lights resemble wings or comets. |
Realistic night-lens imperfection. |
| Bloom |
Bright areas bleed softly into surroundings. |
Atmospheric, not equivalent to blur. |
| Halation |
Warm/red edge glow around intense highlights. |
Film-like highlight behavior. |
| Sensor noise |
Fine luminance or color speckling at high sensitivity. |
Digital low-light realism. |
| Film grain |
Organic density variation with size tied to film stock/format. |
Avoid describing as uniform digital noise. |
| Rolling-shutter skew |
Fast motion or panning bends vertical forms. |
Usually an intentional phone/digital artifact. |
| Moiré |
Interference ripples on fine repeating patterns. |
Usually undesirable. |
| Dust and scratches |
Physical film or scan marks. |
Use sparingly; avoid generic dirt overlay. |
| Light leak |
Colored exposure near film edge. |
Analog accident, often red/orange. |
| Double exposure |
Two exposures overlap into one frame. |
Specify subject hierarchy and blending areas. |
Example combinations#
85mm head-and-shoulders portrait, nearest eye tack sharp, shallow depth of field,
smooth circular bokeh, soft highlight rolloff, no heavy vignette
24mm deep-focus interior, camera level, straight verticals, foreground chair and distant
windows both readable, balanced exposure preserving window detail
200mm panning photograph of a racing motorcycle, rider and bike sharply tracked,
horizontal background streaks, wheels showing rotational blur, no frozen spokes
Use one lens concept and one focus target as anchors. Add artifacts only when they reinforce a deliberate capture method or period.