NiSi Cine Lens Athena Prime 85mm T1.9 RF-Mount

NiSi Cine Lens Athena Prime 85mm T1.9 RF-Mount – T1.9 aperture with Drop-In filter and full-frame coverage

The NiSi Athena Prime 85mm T1.9 in RF mount delivers the optical characteristics of the Athena series tailored for Canon RF cameras. It shares the same design goals as the rest of the Athena Prime line: consistent light transmission, minimized focus breathing, matched handling across lenses, and support for full-frame and large-format sensors.

Key features of the 85mm Athena Prime

• Maximum aperture: T1.9, providing shallow depth of field and soft bokeh for background separation.
• Mount: Canon RF (part of the Athena series available in ARRI PL, Canon RF, Sony E, Panasonic/Leica L and Fuji G).
• Drop-In filter option: RF-mount lenses include the proprietary Drop-In filter system for rear filtration.
• Image circle: 46mm, making the lens suitable for full-frame and large-format sensors.
• Filter thread: 77mm (shared across the series except for the 14mm lens).
• Matched mechanical design: aperture and focus rings are consistent with other Athena primes.

Optical performance and exposure consistency

The Athena series uses T-stop ratings to indicate actual light transmission. For example, the 85mm offers a maximum aperture of T1.9, which means predictable exposure and straightforward matching with other T1.9 lenses in the set. In the broader series, 25/35/40/50 and 85mm are T1.9, 18mm and 135mm are T2.2, and the 14mm is T2.4.

The lenses also control chromatic aberration and micro-contrast, helping to render finer image detail. In addition, the design minimizes focus breathing so that changes in field of view during focus pulls remain very small, regardless of focal length or aperture setting.

Mounts, rear filtration and important notes

The Athena Prime series is available in multiple mounts, and NiSi implements a rear filtration solution across the lineup. Specifically:

• RF, L and G mounts: Drop-In filter option is available.
• E-mount: available in two versions — with and without Drop-In filter.
• PL-mount: uses a rear filter.

Important: always use the Drop-In clear filter on RF, L, G and E mounts, and the rear filter on PL mounts, to achieve infinity focus and obtain clear images. Additionally, Sony FX9 cameras cannot use the E-mount versions that include Drop-In filters.

NiSi also provides weather sealing for the Drop-In filter to maintain reliability in varied shooting environments.

Handling, mechanics and compatibility

NiSi designed the Athena primes with consistent handling in mind. All lenses in the series are similar in weight, so you do not need to rebalance a gimbal when switching between Athena lenses. Both aperture and focus rings are matched across the range for predictable ergonomics.

• Focus rotation: 300°, enabling precise focus pulls.
• Focus scales: fluorescent markings shown in both imperial and metric units for clear visibility.
• Gears: standard 0.8 mod focus and iris gears for compatibility with follow focus and matte box systems.

You can also use the NiSi 77mm close-up lens (sold separately) to reduce minimum focus distance and produce macro effects when needed.

Who this lens is for

This 85mm T1.9 RF-mount lens suits cinematographers and videographers who need a medium-telephoto prime with consistent T-stop exposure, matched handling across a prime set, and support for rear filtration workflows. It integrates into the Athena series where optical consistency and mechanical matching matter for multi-lens shoots.

Smart FAQ

Question: Is the 85mm Athena Prime suitable for full-frame and large-format sensors?
Answer: Yes. The lens projects a 46mm image circle, which makes it suitable for full-frame and even large-format sensors as stated for the Athena series.

Question: Does the RF-mount version include a Drop-In filter and do I need it to focus to infinity?
Answer: The RF-mount Athena Prime supports the Drop-In filter system. You should use the Drop-In clear filter on RF (as well as L, G and E mounts) to achieve correct infinity focus and obtain clear images; for PL mounts use the rear filter.

Question: Will I have to rebalance my gimbal when I switch to this 85mm from other Athena lenses?
Answer: No. All Athena Prime lenses are similar in weight, so they do not require rebalancing when you switch lenses within the series.

Question: How does the lens handle focus pulls and focus breathing?
Answer: The lens offers a 300° focus rotation and fluorescent focus scales in both imperial and metric for accurate pulls. The Athena series is designed to minimize focus breathing, so field-of-view changes during focus adjustments remain very small.

Question: Can I use an E-mount with Drop-In filters on a Sony FX9?
Answer: No. Sony FX9 cameras cannot use the E-Mount version that includes Drop-In filters, as noted for the series.