Irix 11mm f/4 Firefly Ultra-Wide Angle Prime Lens for Pentax K

The Irix 11mm f/4 Firefly is an ultra-wide angle prime lens for Pentax K-mount full-frame cameras, delivering an expansive 126° angle of view for breathtaking landscapes, architecture, and astrophotography. Its advanced optical design with 16 elements in 10 groups, including 4 high-refractive, 3 aspherical, and 2 extra-low dispersion elements, ensures exceptional sharpness and minimal distortion across the frame. The Neutrino coating suppresses flare and ghosting, while the manual focus mechanism with focus lock and infinity click provides precise control for critical focusing.

Advantages

The Firefly combines robust construction with lightweight portability. Its aluminum-magnesium alloy body and weather sealing at three points protect against dust and moisture, enabling reliable shooting in challenging conditions. The built-in petal-type hood reduces stray light and protects the front element. A rear gel filter slot accepts 30x30mm filters for creative effects without the need for large front filters. The hyperfocal scale aids in achieving maximum depth of field for landscape and street photography.

Suitable for

• Landscape and nature photographers seeking extreme wide-angle perspectives
• Architectural and real estate professionals needing minimal distortion
• Astrophotographers capturing star fields and Milky Way panoramas
• Travel photographers valuing lightweight, durable gear
• Videographers requiring smooth manual focus and wide coverage

Key specifications

• Focal length: 11mm
• Maximum aperture: f/4
• Minimum aperture: f/22
• Lens mount: Pentax K
• Format compatibility: Full-frame
• Angle of view: 126°
• Minimum focus distance: 0.28 m (11.02 in)
• Optical design: 16 elements in 10 groups
• Diaphragm blades: 9 (rounded)
• Focus type: Manual focus
• Filter size: Rear gel filter slot (30x30mm)
• Weather sealing: Yes (3 sealing points)
• Special elements: 4 HR, 3 ASP, 2 ED
• Coating: Neutrino coating
• Focus lock: Yes
• Infinity click: Yes
• Hyperfocal scale: Yes
• Material: Aluminum-magnesium alloy, composite
• Hood: Built-in petal-type

Recommendations

Pair the Irix 11mm f/4 Firefly with a sturdy tripod for low-light and long-exposure work. Use the rear gel filter slot for neutral density filters to achieve silky water effects or for light pollution filters in astrophotography. The lens's manual focus and hyperfocal markings make it ideal for zone focusing in street photography.