NiSi Cine Lens Athena Prime 25mm T1.9 Fuji G-Mount

NiSi Cine Lens Athena Prime 25mm T1.9 Fuji G-Mount – T1.9 aperture with Drop-In filter option

The NiSi Athena Cine Lens 25mm T1.9 in Fuji G-Mount is part of the Athena Prime series designed for cinematographers and videographers who require consistent optics and cine-style handling. This 25mm model offers a T1.9 maximum aperture for shallow depth of field and soft bokeh when needed, and it is available with the Athena series’ Drop-In filter system on G-Mount bodies.

Key benefits and intended uses

• Consistent exposure across a matched prime set thanks to measured T-stops.
• T1.9 on the 25mm provides attractive background separation and low-light flexibility.
• Drop-In filter option on G-Mount gives filmmakers flexible filtration and creative control.
• Suitable for a wide range of shooting scenarios, from wide scenes to portraits when paired with other Athena primes.

Optics, aperture and image coverage

The Athena Prime series covers focal lengths from ultra-wide to portrait: 14mm through 135mm. The series provides an image circle of 46mm, making these lenses suitable for full-frame and larger format sensors. Apertures vary across the range and are measured as T-stops for consistent exposure:

• 25mm (this lens): T1.9
• 35mm, 40mm, 50mm, 85mm: T1.9
• 18mm and 135mm: T2.2
• 14mm: T2.4

Mounts, filter systems and compatibility

The Athena Prime series is offered in multiple mount options, including ARRI PL, Canon RF, Sony E, Panasonic/Leica L and Fuji G. Mount-specific filter options are implemented as follows:

• RF-, L- and G-Mount lenses have a Drop-In filter option.
• E-Mount is offered as two versions: one with Drop-In filter and one without.
• PL-Mount uses a rear filter.

Note the important compatibility points:

• Sony FX9 cannot use the E-Mount version with Drop-In filters.
• To achieve infinity focus and clear images, you must use the Drop-In clear filter on RF-, L-, G- and E-mounts, and the rear filter on PL-mounts when using the lenses.
• NiSi provides weather sealing for the Drop-In filter option.

Handling, mechanics and matching across the set

The Athena Primes are designed for predictable, cine-style operation:

• All lenses (except the 14mm) share the same 77mm front filter thread.
• Aperture and focus rings are matched across the range for consistent hand and follow-focus operation.
• Focus rotation is 300° for precise focus pulls, with fluorescent focus scales in both imperial and metric units.
• Standard 0.8 mod focus and iris gears ensure compatibility with common follow-focus and matte box systems.
• All lenses are similar in weight so they do not require rebalancing on a gimbal when switching between Athena lenses.

Optical characteristics and image quality

The series emphasizes controlled aberrations and fine detail rendering. Features include ultra-low chromatic aberration and micro-contrast control to deliver finer image details. The lenses are engineered to minimize focus breathing so the change in field of view when pulling focus—from minimum focus distance to infinity—remains extremely small across apertures and focal lengths.

Optional accessories

• NiSi 77mm close-up lens (sold separately) can reduce minimum focus distance to create macro effects when used with compatible Athena lenses.

Specifications

Frequently Asked Questions

Question: Will the 25mm T1.9 Athena Prime in G-Mount cover full-frame or larger sensors?
Answer: Yes. The Athena series provides a 46mm image circle, which makes these lenses suitable for full-frame and even larger format sensors.

Question: Do I need to use a Drop-In filter to achieve infinity focus on G-Mount lenses?
Answer: Yes. For RF-, L-, G- and E-mount versions with Drop-In systems, you must use the Drop-In clear filter. For PL-mount, use the rear filter. This ensures correct infinity focus and clear images.

Question: Can I swap Athena lenses on a gimbal without rebalancing?
Answer: Yes. All Athena Prime lenses are similar in weight, so switching between them does not typically require rebalancing on a gimbal.

Question: Is the E-Mount version compatible with Sony FX9 when using Drop-In filters?
Answer: No. The Sony FX9 camera cannot use the E-Mount version that includes Drop-In filters.

Question: How are the focus and aperture controls laid out for follow focus systems?
Answer: The lenses feature matched aperture and focus rings, 300° focus rotation, fluorescent imperial and metric focus scales, and standard 0.8 mod gears for compatibility with common follow-focus and matte box systems.