NiSi Cine Lens Athena Prime 50mm T1.9 RF-Mount

NiSi Cine Lens Athena Prime 50mm T1.9 RF-Mount – T1.9 aperture for soft bokeh and consistent T-stops

The NiSi Athena Prime 50mm T1.9 in RF-Mount is part of the Athena Cine Lens series designed for cinematographers and videographers who need precise optics and consistent performance. This 50mm prime shares the same design language and mechanical specifications as the rest of the Athena range, helping you maintain a uniform workflow across focal lengths.

Key optical characteristics

The Athena Series covers a broad set of focal lengths from ultra-wide to portrait primes. This variety gives you flexibility for many shooting scenarios.

• Focal length range: 14mm to 135mm, covering super-wide to portrait focal lengths.
• T-stop consistency across the range ensures reliable exposure matching between lenses.
• Specific maximum T-stops:
  • 25mm, 35mm, 40mm, 50mm & 85mm: T1.9 for shallow depth of field and soft bokeh.
  • 18mm and 135mm: T2.2.
  • 14mm: T2.4.
• Image circle: 46mm, suitable for full-frame and large-format sensors.
• Optical control: ultra-low chromatic aberration and micro-contrast control for finer image detail.

Mount options and filter system

The Athena series supports multiple mounts and offers a proprietary rear filtration solution for creative flexibility. Pay attention to mount-specific filter requirements to achieve infinity focus and clear images.

• Available mounts: ARRI PL, Canon RF, Sony E, Panasonic/Leica L and Fuji G.
• Drop-In filter system:
  • RF-, L- and G-Mount lenses include a Drop-In filter option.
  • E-Mount is available in two versions: with Drop-In filter and without Drop-In filter.
  • PL-Mount uses a rear filter rather than a Drop-In option.
• Important compatibility notes:
  • 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- & E-mounts and the rear filter on PL-mount lenses.
• NiSi provides weather sealing for the Drop-In filter to protect the mounting area and filter element.

Handling, mechanics and consistency

The Athena primes prioritize consistent handling and smooth operation, which reduces rigging time and simplifies lens changes on set.

• All Athena Prime lenses are similar in weight, so you do not need to rebalance a gimbal when switching between them.
• Filter thread: all lenses except the 14mm share a 77mm front filter thread.
• Aperture and focus rings are matched across the range for consistent tactile feel.
• Focus rotation: 300° for precise manual focus pulls.
• Focus scales: fluorescent markings in both imperial and metric units for easy reading in low light.
• Gear standard: standard 0.8 mod focus and iris gears for compatibility with follow focus and matte box systems.

Additional accessories and options

NiSi offers accessories to extend the lenses' functionality and creative range.

• NiSi 77mm close-up lens (sold separately) can reduce the minimum focusing distance and enable strong macro effects on compatible lenses.

Technical specifications

FAQ

question: Is the 50mm Athena Prime compatible with full-frame and large-format cameras?
Answer: Yes. The Athena series has a 46mm image circle, which makes the lenses suitable for full-frame and large-format sensors.

question: Do I need a special filter to reach infinity focus with RF, L, G or E mounts?
Answer: Yes. To obtain infinity focus and clear images you must use the Drop-In clear filter on RF-, L-, G- and the E-mount (if using the Drop-In version). For PL-mount lenses, you must use the rear filter provided for that mount.

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

question: Does the E-mount version work 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, so check mount and camera compatibility before purchasing.

question: How do I get closer focus or macro-like results with the Athena lenses?
Answer: NiSi offers a 77mm close-up lens (sold separately) that reduces minimum focus distance and helps create strong macro effects on compatible lenses with a 77mm filter thread.

This 50mm T1.9 RF-mount lens delivers the matched mechanics and consistent optical characteristics of the Athena series, making it straightforward to integrate into multi-lens kits and production workflows.