This lens is included fisheye function 180 degree at 10mm and ultra wide 100 degrees at 17mm. Sure, there is lots of distortion in 10mm because it is fisheye, but it is not a bad point you cab create many creative photo from it. At 17mm, you can take 100 degree with just a few distortion.

Both fisheye and ultra wide in the same lens; good build quality

Cannot install filter; an unique design of lens cap if lost it have to pay much for it

An unusually well made fun lens which has full metal construction even the inner barrels.

Full metal barrels; decent sharpness across the frame

Visible CA

This is a very fun lens to use. It provides full frame images on a digital slr through the entire zoom range. It is about the equivalent of a 15-26mm lens on a 35mm camera. It is a great match for the 18-55 kit lens that comes with most Pentax digital cameras.

Compact size; Good quality optics; Smooth operation; Zoom

No filter system; Only useable on digital cameras

"I would like to start by stating am a very amateur photographer. I have read many reviews about extra wide vs. fisheye lenses. I do not have an extra wide angle lens and so I relied on online reviews to make my choice.

This is an excellent lens, perfect for multiple uses. It is perfect for landscape photography, live band photography and has displayed amazing results with nighttime photography. I've been using this on my K-5 alongside the 18-135mm lens and it has become my favourite lens yet!

I orginally wanted a wide angle and rented this lens since the wide angle was unavailable. The lens is a great fun lens and you can do a lot of creative shots. Great for night photography if you have a subject that has a lot of curvature.

v This strange lens offers the distorted view of a fisheye lens, with the convenience of a zoom lens. It offers a 180degree field of view, from corner to corner when set at 10mm and the equivalent of a 25.5mm lens on a 35mm camera, with lots of barrel distortion, at 17mm.

Expensive for the quality. At Lowest 10mm on the edges see lot of curvature / distortion. Not worth the 50k I paid for this.

I was wary of buying this lens, as a fisheye is quite a niche item. However, I am delighted. I also have the Pentax 12-24mm and at the same focal lengths it is just as good, though this is fisheye so looks a lot wider.

Consistent Output; Lightweight; Quick Focus; Sharp Focus