How do video lenses differ from photography lenses?

On set, a cine lens functions as a calibrated component in a repeatable system. Teams expect precise T-stop transmission, long mechanical throws, minimal focus breathing, and accessories that swap without re-rigging. By contrast, stills lenses typically emphasise autofocus speed, compactness and firmware correction. Below is a technical walkthrough of what separates motion-first optics from photo glass, with concrete examples you can evaluate today.

T-stops vs f-stops: exposure that matches across cameras

Stills lenses are marked in f-stops (a geometric ratio). Motion work relies on T-stops, which measure real light transmission after losses in elements and coatings. Matching exposure across bodies, scenes and lighting states requires T-rated optics. A practical example is the DZOFilm Arles 50 mm T1.4: when set to T2.8, it delivers the same illuminance the meter expects—no guesswork during multi-camera shading. Its 16-blade iris and large 95 mm front support robust filtration and smooth bokeh shaping.

DZOFilm Arles 50 mm T1.4 FF/VV — full-frame cine prime with 16-blade iris and 95 mm front.

Mechanical precision that supports crews

Cine barrels provide a long, predictable focus throw (often 270–300°), industry-standard 0.8-MOD gears on focus/iris/zoom, and engraved witness marks readable from both sides. The DZOFilm Vespid Prime 50 mm T2.1 offers a 270° focus rotation, an 80 mm front and a 16-blade iris. It covers Ø46.5 mm (FF/VV) and shows very low breathing, so a rack from 0.46 m (≈1.6 ft) to infinity doesn’t look like a zoom.

DZOFilm Vespid Prime 50 mm T2.1 — compact FF/VV cine prime with 270° focus throw and minimal breathing.

Focus breathing control

Breathing—apparent angle-of-view change while focusing—breaks continuity in narrative and draws attention in live cuts. Cine optics use floating groups and more telecentric layouts to restrain it. The Vespid 50 mm keeps framing stable; the Arles 50 mm uses a floating block that preserves edge resolution as you move in, keeping geometry consistent for A/B intercuts and VFX tracking.

Parfocal architecture and constant aperture zooms

In motion, a zoom should hold focus and transmission across the range. The DZOFilm Pictor 20–55 mm T2.8 / 50–125 mm T2.8 pair are parfocal Super 35 zooms: focus set at 50 mm remains locked at 125 mm, and illumination stays at a true T2.8. Both maintain matched 95 mm fronts and aligned gear positions, so swaps don’t force motor re-rigs. Close focuses are 0.60 m (≈2.0 ft) and 0.80 m (≈2.62 ft) respectively, covering interviews, gimbal work and handheld moves with one kit.

DZOFilm Pictor Zoom Kit — parfocal S35 coverage, constant T2.8, unified 95 mm fronts.

Anamorphic capture: squeeze ratio and flare palette

Motion teams often need anamorphic character—oval bokeh, horizontal flares and a wider shot on the same sensor area. The Laowa Nanomorph 85 mm T2.9 1.5× LF (Amber) maintains a constant 1.5× squeeze from 0.70 m to infinity, avoiding geometry shifts across the focus range. Its amber flare treatment yields controlled streaks with preserved contrast, and the 270° focus travel plus dual scales enable accurate marks on dollies or shoulder rigs.

Laowa Nanomorph 85 mm T2.9 LF — constant 1.5× anamorphic, controlled amber flares, 80 mm front.

Cine zoom ecosystems and format flexibility

Beyond parfocality, some zooms offer modular format options. The Laowa OOOM 25–100 mm T2.9 covers Super 35+ natively. The bundle adds a 1.4× expander to lift the image circle to ≈46 mm for full-frame, and a 1.33× rear anamorphic adapter to deliver 2.4:1 on 16:9 sensors. Internal focusing/zooming keep balance stable on gimbals, while the 300° focus rotation provides fine control for marks. Minimum focus is 0.60 m (23.6″), suitable for tabletop and product work without diopters.

Laowa OOOM 25–100 mm T2.9 — internal mechanics, parfocal behaviour, modular adapters for FF or scope output.

Broadcast servo zooms for ENG and studio

Electronic newsgathering and studio chains use B4-mount power zooms with servo demand, return video and 2× extenders. The Fujinon UA18x7.6BERD spans 7.6–137 mm (15.2–274 mm with the extender), holds F1.8 at the wide end and integrates 16-bit encoders for virtual graphics pipelines. Minimum focus is 0.60 m (≈2.0 ft). Features such as anti-backlash gearing, cruise zoom and serial digital control keep motion smooth in fast-turnaround news and sports.

Fujinon UA18x7.6BERD — 18× ENG zoom with built-in 2× extender and full servo control.

Mount standards and front diameters

Motion sets standardise PL mount and shimmable mirrorless plates to lock flange depth. Equally important is a shared front diameter: 80, 95 or 114 mm fronts support the same clip-on matte boxes and donuts across lenses. In practice, the Arles primes keep 95 mm fronts (M86 filter), the Pictor zooms also use 95 mm, while Nanomorph LF primes use 80 mm fronts with 77 mm threads. That uniformity reduces swaps and prevents motor repositioning mid-take.

Continuous, linear iris control

A cine iris ring is stepless and linearised for transmission, allowing smooth exposure ramps under dimmers or LED walls. Vespid’s iris travels ~58°, Arles around 80°, and OOOM ~50.5°, each calibrated to meters rather than camera firmware. That predictability matters for HDR pipelines, live switching and chroma work.

Optical construction for motion

Cine primes and zooms favour internal focusing, floating groups and near-telecentric exit pupils. These choices keep the optical centre steady, suppress focus breathing and hold contrast with practicals in frame. Multi-blade irises (13–16 leaves in the examples above) yield round specular bokeh and smooth transitions, while coatings are tuned to manage flare without crushing highlight detail.

Why photo glass struggles in video

Focus-by-wire, short throws and aggressive focus breathing make critical marks difficult. Exposure often ramps across a zoom. Extending barrels disturb gimbal balance. Witness marks are sparse or absent. Cine lenses answer with repeatable mechanics, de-clicked, geared aperture control, and matched colourimetry across sets—so editors aren’t chasing white balance and contrast in post.

Example configurations

Compact FF/VV prime for day-to-day work: DZOFilm Vespid Prime 50 mm T2.1. Ultra-fast look for low-light or selective focus: DZOFilm Arles 50 mm T1.4. Two-zoom S35 kit for run-and-gun: DZOFilm Pictor 20–55/50–125 mm T2.8. Modular zoom for scope/FF flexibility: Laowa OOOM 25–100 mm T2.9. ENG/Broadcast power zoom: Fujinon UA18x7.6BERD.

Conclusion

What separates a cine lens from a stills lens is not marketing—it is behaviour under motion: verified transmission, repeatable mechanics, restrained breathing and reliable parfocal zooming. Choose optics that respect those constraints and your lighting, focus pulling and live switching remain consistent from slate to slate.