Irix 15mm F2.4 Now Available for Pentax

Premium ultra wide prime designed for full-frame cameras

By PF Staff in Third-Party Announcements on Nov 21, 2016

A new lens has recently made its debut in the Pentax K-mount: the Irix 15mm F2.4 ultra wide angle.  Following an October launch in the Canon and Nikon mounts, it is now also shipping for Pentax.

This manual focus, auto-aperture, nano-coated lens is designed to deliver premium image quality and covers the full frame image circle.  It has recently been the subject of a 400+ post discussion on the forum, and it has attracted plenty of attention as a possible alternative to the Pentax D FA 15-30mm F2.8 zoom for the Pentax K-1.

The Irix 15mm is the first third-party lens with the Pentax K-mount to feature weather sealing.

It is available in two variants that share the same optics: a cheaper "Firefly" (with a plastic body, barrel weather sealing, lighter weight), and the premium "Blackstone", (with a metal barrel, engraved text, full weather sealing).  Pricing is set at 475 and 695, respectively (roughly $504 and $738 at today's exchange rates).  Currently, the lenses are sold exclusively through the Irix web site, but this is subject to change.

Irix is a Swiss lens designer, while its lenses are produced in Korea.  According to the manufacturer:

"Swiss precision and ingenious Korean solutions make for a powerful combination. Irix lenses are designed to deliver top optical performance and match the demands of full frame matrix cameras. Our wide-angle lenses successfully merge a short focal length with a large aperture. Our intelligent build combined with high quality coatings result in minimal distortion. With this guarantee, your Irix lens will quickly become your go-to tool."

We've uploaded the 15mm's full specifications to our lens database, where you can learn more about both versions of the lens:

Irix 15mm F2.4 Firefly | Irix 15mm F2.4 Blackstone

Samyang Announces 20mm F1.8 Lens in K-mount

Samyang expands their line of wide angle prime lenses

By PF Staff in Third-Party Announcements on Aug 11, 2016

Samyang has announced the Samyang 20mm F1.8 ED AS UMC fast ultra-wide angle lens in Pentax K-mount. The lens will also be available in various other mounts.

This new lens is a welcome addition to their already extensive line of wide angle lenses and is of particular interest for Pentax users, since Pentax currently offers no ultra wide angle prime lenses in the 24x36mm full-frame format. A 20mm focal length is suitable for landscape photography and for astro photography so this lens fills a void.

The lens has the KA variant of the K-mount which means that it is manual focus only and that it has an aperture ring with an "A" setting. It can thus be used on any and all Pentax bodies, film as well as digital, and supports all exposure modes provided by the body (P, Av, Tv, M, etc.).

The lens has a fast maximum aperture of F1.8 which makes it weigh in at a hefty 493 grams (17.4 oz). For comparison the discontinued and about 1.5 stops slower smc Pentax-FA 20mm F2.8 only weighs 255 g (9 oz). The Samyang measures 83 mm in diameter and is 87 mm from front to mount.

Sigma Announces Lens Mounting Issue with K-70

Minor scratch to the camera body possible

By PF Staff in Third-Party Announcements on Aug 9, 2016

Sigma Japan has posted a product advisory warning customers that when select Sigma lenses are attached to the Pentax K-70, a minor scratch to the camera's lens mount may be inflicted. This notice applies to the following lenses:

Sigma advises customers to send in the affected lenses for free repairs at an authorized Sigma service center.  Sigma will also soon offer to repair affected K-70 bodies at no charge.

This same notice was issued for the Pentax K-1, along with a corresponding repair service.

The Damage

Many Sigma lens mounts have flanges with a larger outer diameter than genuine K-mount lenses.  Since this flange can extend beyond the mount on the camera, it can come into contact with the camera body and cause a scratch, even after a single mounting.

This issue currently only affects the K-1 and K-70.  To address the problem, Sigma is replacing the flanges with ones that won't come into contact with the camera body.

An example of the resulting scratch is shown below:

Sigma Announces Lens Compatibility Issues with K-1

Many recent lenses can potentially cause mount damage

By PF Staff in Third-Party Announcements on May 11, 2016

Sigma Japan has posted a product advisory warning customers that when select Sigma lenses are attached to the Pentax K-1, a minor scratch to the camera's lens mount may be inflicted. This notice applies to the following lenses:

Sigma advises customers to discontinue use of the affected lenses. The company plans to offer a repair service at a future date to address the issue.

In addition, Sigma states that the K-1 many not be able to correctly determine the correct image circle of Sigma lenses when the crop mode is set to "auto".  Manual configuration of the crop setting is therefore recommended.

On an unrelated note, user reports suggest that certain older Sigma lenses cause the K-1 to freeze after being mounted— including the 70-200mm F2.8 EX DG APO Macro HSM II.  A firmware update for the affected lens(es) may be necessary to rectify this issue.

How the K-1 Mount Differs

While the Sigma press release does not explicitly describe the nature of the potential damage to the camera, a likely scenario is that the area directly above the lens mount gets scratched. The K-1's larger prism housing protrudes farther beyond the lens mount than other Pentax bodies and it is also angled more steeply, which could lead to scrapes while mounting lenses designed without this in mind.

We can only speculate whether this issue is related to improper mount implementation (reverse-engineering) by Sigma, or an internal change to Pentax's own mount specifications.

To date we do not know of any incompatibilities or issues with genuine Pentax lenses and the K-1.

Speaking of other mount differences, the K-1's focusing screen foam is situated much closer to the edge of the bayonet mount compared to Pentax APS-C bodies.  This foam spans the entire width of the mirror, rather than having a gap in the middle as on film SLRs such as the MZ-S.  The retaining clip for the focusing screen is also more exposed than on other Pentax bodies.  These differences don't seem to be causing any issues, however— nor should they.

K-3 Mount (left) vs K-1 Mount (right)

Sigma 18-300mm "C" Release Date Set

To be launched on August 21 per Sigma Japan

By PF Staff in Third-Party Announcements on Aug 12, 2015

In a press release dated August 7th, Sigma Japan announced that the Sigma 18-300mm F3.5-6.3 DC Macro HSM "Contemporary" lens will start shipping in the Pentax mount on August 21st. 

Learn more about the 18-300mm lens in the original announcement

This all-in-one superzoom range offers a class-leading focal length of 300mm at the long end.  It has been available for Canon, Nikon, and Sigma for nearly a year.  The Pentax version can be pre-ordered at B&H Photo for $579.

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