I have purchased the Pentax HD DA 11-18mm f/2.8 ED DC AW lens a year ago and wanted to use it as main wide angle lens. After a year I have to admit it is great lens especially when used on my Pentax K3-iii camera. To briefly summarize my experience I can describe the lens as follows:
Firstly, the lens is designed specifically for Pentax APS-C format cameras and provides an equivalent focal length of around 17-27mm in full-frame terms. I have been using it with Pentax K3-iii. The lens is not very compact and lightweight as I was used to previous wide angle lens 15 mm limited of the same producer. However, its capabilities make it easy to carry around for all kinds of photography, especially landscape and architecture.
In terms of image quality, the lens is known for delivering sharp and crisp images, even at the edges of the frame. The lens has several optical elements, including Extra-low Dispersion (ED) glass, to reduce chromatic aberrations and improve colour accuracy. The lens coatings also help to reduce ghosting and flare, resulting in clear and contrast images.
The lens' wide maximum aperture of f/2.8 allows for excellent low-light performance, allowing you to shoot in dimly lit environments without having to rely on high ISO settings. Additionally, the lens' fast autofocus system and quiet motor make it ideal for shooting in both still and video modes.
The lens' weather-sealed construction also provides added protection against the elements, making it a reliable option for outdoor photography. Its compact and lightweight design also make it easy to carry around and use for extended periods.
Overall, the Pentax HD DA 11-18mm f/2.8 ED DC AW lens is an excellent choice for wide-angle photography with your Pentax K3-iii camera. Its superb image quality, fast and reliable autofocus, and durable construction make it a highly recommended lens for photographers looking to expand their creative possibilities.