Irix 15mm f/2.4 Blackstone Pentax

Great lens, very well built and brilliant optics. I have used many ultra wide lens over the years from Sigma and Nikon this one beats them all. Perfect for wide landscapes and astrophotography. Very close focusing. The lockable focus ring allows for easy hyperfocal focussing, allowing you to shoot effortlessly between infinity to less than m at f without touching the focus ring. I cannot recommend this lens enough. Outstanding

I was looking for reasonably price wide angle prime to use on Nikon APS-C DSLR (so the mm was in effect .mm). I shoot landscape predominantly and the weather sealing was a major factor in deciding to get this lens. Didn't need autofocus so it being manual wasn't an issue. The positive 'click' for the infinity setting was useful, stopped checking focus as much as normal as day progressed. Tested it for astro work and it performed well. Genuine feel of quality when using, optics worked well, barely visible vignetting, occasional flare when pointed in similar direction to the sun, but that is hardly unexpected for such a wide angle. Horizon line distortion was not at issue, incredible really. Used with Cokin X-Pro filters and had no issues with them impinging on field of view, you couldn't get away with using Z-Pro series though, so if you want to use filters with this lens its not a cheep option. I'll definitely buy IRIX again, looking forward to seeing what they do next.

Absolutely love this lens, super sharp on the Pentax K1ii and really easy to focus. Was not to sure about this or the 11mm but decided on the 15mm as I thought the 11mm would be to wide and am glad I decided in the 15mm..especially since it accepts filters.

Apart from the infinity not being set accurately, which is easy enough to adjust, the lens is excellent.

Irix made a splash when they launched the 15mm F2.4. With its wide angle, fast aperture, claims of high optical performances and, most importantly, support for Pentax's K-mount, it drew the attention of many.