SKU: 72119064718

IRIX 11mm f/4 Firefly Lens for Pentax K

Sale price$26496.00 Regular price$29440.00
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Description

IRIX 11mm f/4 Firefly Lens for Pentax KPentax K Mount Full Frame Format Aperture Range: f 4 to f 22 Three Aspherical Elements Two ED and Four HR Elements Neutrino Coating Manual Focus Design with Focus Lock Rubberized Focus Ring Depth of Field and Focus Distance Scales Weather Sealed ABS Plastic Housing Rounded Nine Blade Diaphragm A versatile ultra wide prime lens, the Pentax K mount 11mm f 4 Firefly Lens from Irix balances a sophisticated optical design with a lightweight, durable

  • Pentax K-Mount/Full-Frame Format
  • Aperture Range: f/4 to f/22
  • Three Aspherical Elements
  • Two ED and Four HR Elements
  • Neutrino Coating
  • Manual Focus Design with Focus Lock
  • Rubberized Focus Ring
  • Depth of Field and Focus Distance Scales
  • Weather-Sealed ABS Plastic Housing
  • Rounded Nine-Blade Diaphragm

A versatile ultra-wide prime lens, the Pentax K-mount 11mm f/4 Firefly Lens from Irix balances a sophisticated optical design with a lightweight, durable physical construction. Aspherical, extra-low dispersion, and high-refractive index elements are used to suppress color fringing, chromatic and spherical aberrations, as well as unwanted distortion, and also contribute to producing a high degree of sharpness and clarity. Additionally, a Neutrino coating has been applied to limit lens flare and ghosting for improved contrast and color accuracy when working in strong lighting conditions.

In addition to the imaging performance, this 11mm f/4 utilizes a manual focus design for fine-tuned control, and incorporates a unique positive focus lock to secure the focusing position at any point for consistent, repeatable shooting. As the Firefly version of this focal length, this lens is also distinguished by a lightweight ABS plastic exterior, printed lens markings, and weather-sealing about the lens housing to permit working in trying environmental conditions.

The Firefly version of the 11mm f/4 lens features a lightweight ABS plastic exterior construction that is sealed against moisture and dust along the main body of the lens. The Firefly construction also incorporates a rubber focus ring for improved grip and control, and has printed focus distance and depth of field scales to aid working with pre-focusing and hyperfocal focusing techniques.
Ultra wide-angle prime designed for full-frame Pentax K-mount DSLRs, this lens can also be used on APS-C models where it provides a 16.5mm equivalent focal length.
Three aspherical, four high-refractive index, and two extra-low dispersion elements are featured within the optical design to limit both spherical and chromatic aberrations, as well as color fringing and distortion, for improved clarity, sharpness, and even illumination.
A Neutrino coating has been applied to limit lens flare and ghosting for improved contrast and color fidelity.
Manual focus designed is benefitted by a positive focus lock mechanism to secure your focus position at any point to limit unwanted shifting of focus.
A hard click stop indicates the infinity position on the focus ring for easy use in low-visibility conditions.
Large depth of field scale benefits using hyperfocal and pre-focus techniques.
Built-in petal-shaped lens hood blocks stray light in order to reduce lens flare, and also protects the front element of the lens.
Rear of the lens accepts 30 x 30mm cut gel filters.
Rounded nine-blade diaphragm contributes to smooth bokeh.
In the Box
IRIX 11mm f/4 Firefly Lens for Pentax K

IRIX 11mm f/4.0 specs

Performance
Focal Length 11mm
Aperture Maximum: f/4
Minimum: f/22
Camera Mount Type Pentax K
Format Compatibility 35mm Film / Full-Frame Digital Sensor
Angle of View 126°
Minimum Focus Distance 10.83" (27.5 cm)
Elements/Groups 16 / 10
Diaphragm Blades 9, Rounded
Features
Autofocus No
Physical
Filter Thread Rear Gel:
Dimensions (DxL) Approx. 4.65 x 4.06" (118 x 103 mm)
Weight 1.61 lb (730 g)
Packaging Info
Package Weight 3.15 lb
Box Dimensions (LxWxH) 7.3 x 5.9 x 5.6"
All product and company names are trademarks™ or registered® trademarks of their respective holders. Use of them does not imply any affiliation with or endorsement by them.
Shipping Notes
  • Free Standard Shipping on $100+ Orders to the USA.
  • Except Preorder products are shipped in 48 hours.
  • Delivery to the USA:
  1. Standard Shipping : 3-10 business days
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Exchange/Return Notes
  • We offer a 30-day return/exchange service after receiving.
  • Final sale items are not eligible for returns or exchanges.
  • To process your return/exchange, please contact us at [email protected]
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SKU: 72119064718

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4.6 ★★★★★
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Verified Purchase
LindyB
Carnegie, US
★★★★★ 5
Great dressy sneaker to wear with business casual or jeans
Size: 11, Color: British Tan/Ivry
I got these for my husband to wear with jeans or business casual dress pants. They look sharp and professional and dress up jeans if you're going out. He says they fit comfortably and he can walk on them all day without his feet hurting. They are beautiful genuine leather so they don't get stinky. I got my husband's normal size and they fit to size.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on February 11, 2026
T
Verified Purchase
timothy scalabrelli
Battle Creek, US
★★★★★ 4
Comfortable
Size: 9, Color: Black/Ivory
Most comfortable and roomy shoes I ever wore. Great for insoles. Looks nice too. The base of the shoe is a bit too thick but it’s fine.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on September 5, 2025
B
Verified Purchase
BBZ
Lake Worth, US
★★★★★ 5
Very nice, but sizing is inconsistent
Size: 10 Wide, Color: Ivory/White/British Tan
All of these Cole Haan shoes are extremely well made and I like the styling. On the other hand, the sizing is very inconsistent and you may end up having to do a lot of returns trying to find the right size. Then if you get a different color of it, you may find the sizing different yet again. If you find your right zie, they are really nice shoes at a very reasonable price for the quality.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on February 6, 2026
L
Verified Purchase
Lofidelityrockr
Dallas, US
★★★★★ 5
I love this brand. These shoes look and fit great!
Size: 13 Wide, Color: Black/White/Black
I love wearing Cole Haan shoes. This is the second pair I’ve owned and the style just gets me. I’ve worn these to work at a great professional job every day, not just casual Friday. I wear these when I head out shopping or to dinner. They are functional, comfortable, built for regular and bigger wider feet and comfortable. I am 6 feet tall and my feet have changed size over the years to me needing a wider shoe to relieve pressure on my toes and front wide porting of my foot. So the 13W feels great and still walks the same as a regular 14 but more comfort for me. They look amazing and qualify in some offices as dress shoes (depending on company rules they will justify a sneaker as a shoe with the tan colored “gum” sole as a sneaker) so check company policy. The black sole on this makes it look more dressy. I am switching out the laces to match my previous Cole Haan because I think the white shoelaces look better. As an adult, aside from my Kenneth Cole boots Reaction boots and Doc Marten’s these are the only shoes I will pay 3 digits for. This looks like skater shoes but with a more mature look.
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Reviewed in the United States on December 19, 2025
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Verified Purchase
BWolfeJR
Natrona Heights, US
★★★★★ 5
I am certainly glad I found them and finally ordered
Size: 10, Color: Ivory/White/British Tan
A bit bulkier than my Stan Smiths Leather versions, but actually more comfortable. They seem to be a bit "clunkier" looking than a streamline Stan Smith, but it's a matter of style. It works for a change of pace. Gets or picks up dirt a bit, but cleans well, except the canvas part. Has lasted almost 6-8 months with very little signs of wear. Feels very secure in any type of weather or condition. Great alternative or addition to having a pair of Stan Smiths.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on May 12, 2026

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