Technical Parameters in Prompts: Aspect Ratio, Lens, ISO, Depth of Field

Technical parameters carry a specific kind of information that is qualitatively different from subject and lighting descriptions. They don’t describe what is in the image — they describe the optical and mechanical conditions under which the image was captured. This makes them finishing instructions rather than foundational ones. If you lead with "f/1.4 shallow depth of field, 85mm lens, 1/2000s shutter" before describing what the image is of, the model has no subject to apply the optics to, and the technical terms lose their anchoring. Place technical parameters after subject, composition, lighting, and style so they operate as refinements on an already-established visual scene. There is also a coherence principle: technical parameters work as a group. An aperture of f/1.4 implies shallow depth of field; a high ISO implies grain; a slow shutter speed on a moving subject implies motion blur. When your technical parameters are internally consistent — they tell the same optical story — models reproduce that story reliably. When they contradict each other ("f/22 deep focus with creamy bokeh background"), the model produces an averaged result that satisfies neither instruction. Check your parameters for physical coherence before submitting.

Aspect ratio determines the shape of the image and implicitly defines its intended use and compositional conventions. On Floniks, aspect ratio is controlled in the generation panel directly rather than via text prompt alone — this is more reliable than text-based ratio hints. But understanding what each ratio signals is important for choosing the right one.

• 1:1 (square) — social media, Instagram grid, editorial insets; forces centered or symmetrical compositions
• 4:5 (portrait-leaning) — Instagram portrait feed, strong vertical compositions, shows full figure without cropping
• 9:16 (vertical video / Reels / TikTok) — mobile-first content, tall verticals; subjects should be centered with headroom
• 16:9 (cinematic widescreen) — YouTube, landscape photography, wide establishing shots, cinematic two-thirds compositions
• 2.39:1 (anamorphic / ultra-wide) — scope cinema, very wide panoramic landscapes, conveys epic scale
• 3:2 (standard photography) — traditional DSLR frame, editorial, print photography

For AI video on Floniks /ai-video, choose 16:9 for landscape video or 9:16 for vertical video content. The composition in your prompt should align with the ratio: wide-format prompts should use lateral compositional references (rule of thirds left-right); vertical-format prompts should use vertical layering (foreground, mid-ground, background stacked vertically).

Focal length is the single most useful lens parameter in a prompt because it determines two things simultaneously: field of view (how much of the scene is visible) and perspective compression (whether the background appears close to or far from the subject). Models have absorbed enough photography knowledge to respond meaningfully to these conventions:

• 14–24mm (ultra-wide) — dramatic environmental context, strong perspective distortion, large scene relative to subject; used in architecture, landscape, photojournalism
• 35mm — closest to human eye perspective, street photography, environmental portrait, slight wide feel without distortion
• 50mm — natural perspective, versatile, the "standard" lens; editorial, documentary
• 85mm — the classic portrait focal length; slight compression, flattering for faces, separates subject from background well
• 105mm–135mm — stronger background compression, medium telephoto, fine art portrait
• 200mm+ — heavy compression, makes background feel close and out-of-focus; wildlife, sports, paparazzi-style candids

For prompt use: "shot on an 85mm lens" or "85mm portrait lens" is sufficient. If you want the compression and bokeh effects explicitly, add "slight background compression, subject separated from background" after the focal length.

Aperture controls depth of field — how much of the image, from foreground to background, is in sharp focus. In a prompt, aperture values (f-stop) are a direct way to specify the look:

• f/1.2–f/1.8 (very wide aperture) — extremely shallow depth of field; subject sharp, everything else soft; the "portrait bokeh" look; dramatic subject isolation
• f/2.8 (wide aperture) — shallow depth of field, sharp subject, softly blurred background; versatile portrait and fashion aperture
• f/5.6 (mid aperture) — moderate depth of field; subject and some environmental context in focus; documentary and street photography
• f/8–f/11 (sweet spot) — broad depth of field; sharp from foreground to background; landscape, group portraits, product close-ups where full detail matters
• f/16–f/22 (narrow aperture) — very deep focus; everything sharp from very close to very far; landscape photography, technical product imagery

Phrase it clearly: "shot at f/1.8, extremely shallow depth of field, subject in sharp focus, background creamy and blurred." The words "shallow depth of field" and "creamy bokeh" reinforce the f-stop value and help the model understand the intention even if the f-number alone is ambiguous in context.

ISO controls light sensitivity and introduces grain (digital noise) at high values. Shutter speed controls motion blur. Both are useful prompt parameters for controlling photographic texture and a sense of time:

ISO:

• "Low ISO (ISO 100–400)" — clean, grain-free image; commercial, studio, and daylight photography
• "High ISO (ISO 1600–6400)" — visible grain/noise; documentary, low-light, reportage aesthetic
• "ISO 3200, film grain, monochrome" — the classic black-and-white street photography look
• "ISO 800, slight grain, warm tones" — the look of a consumer film camera in decent light, nostalgic

Shutter speed:

• "1/2000s, motion frozen, sharp action" — sports, wildlife, any fast movement captured crisply
• "1/60s, slight motion blur on hands" — subtle life and movement in otherwise static scenes
• "1s long exposure, light trails" — night photography with car headlight trails or star trails
• "30s, silky smooth water, long exposure" — waterfall or ocean photography with a misty, smoothed water effect

For AI image prompts, shutter speed is most effective when paired with a specific moving element: "1/1000s, water droplets frozen mid-splash" gives the model both the speed and the subject to apply it to. Abstract shutter speed specifications without a moving element may be ignored.

Naming a specific camera body or film stock carries a dense bundle of aesthetic associations that operate as a shorthand style layer:

Camera body references:

• "Shot on Hasselblad medium format" — very high resolution, slightly square crop, premium sharpness, expensive-looking
• "Shot on Leica M" — street photography, slightly clinical sharpness, reportage aesthetic
• "Shot on Sony A7 IV" — modern, clean, commercial quality
• "Shot on a disposable camera" — light leaks, slightly over-exposed, lo-fi, nostalgic
• "Shot on Super 8 film camera" — warm, heavily grained, flickering, home-movie aesthetic

Film stock references:

• "Kodak Portra 400" — warm, slightly desaturated, beautiful skin tones, slight grain, professional portrait film
• "Fujifilm Provia" — saturated, punchy colors, slightly cool, landscape and travel photography
• "Kodak Tri-X 400" — high-contrast black and white, visible grain, the classic street photography film
• "Fujifilm Velvia 50" — hyper-saturated, punchy, nature and landscape use
• "Lomochrome Purple" — color-shifting, surreal, purple tones in foliage, dream-like

Use camera and film references as part of your style layer at the end of the prompt. "Shot on Kodak Portra 400, scanned from 35mm negative, slight natural grain, warm lifted shadows" gives the model a complete photographic character description in one sentence.