Have you ever wished for a do-over on a project? Sometimes you finish up a project and realize that maybe you should have done something a little different. Well, this one of those situations. After completing the comparative review of the Pentax 12-24mm, Sigma 12-24mm, and the Tamron 10-24mm, a lot of forum members said that we should have selected the Sigma 10-20mm, instead of the Sigma 12-24mm. Well you can’t rewrite history, but you can to listen to your forum members. We listened!
In this comparative review, we will take a detailed look at the two Sigma 10-20mm lenses that are currently available. The Sigma lenses are considered ultra-wide angle lenses. A wide-angle lens, by definition, has a focal length shorter than the long side of the camera sensor. The APS-C sensor, used in all Pentax DSLR’s, is approximately 24 mm x 16 mm. This means that any lens with a focal length between 24mm and 16mm is considered wide angle. An ultra-wide angle lens has a focal length less than the short side of the camera sensor. All ultra-wide angle lenses provide the photographer a wider view, with some distortion, which is the appeal of the ultra-wide angle lens.
Ultra-wide angle lenses come in two types: Fisheye lenses with curvilinear barrel distortion and rectilinear lenses. Fisheye lenses are very useful in some situations and can create unique photographs because of their distortion. Rectilinear lenses are designed so straight lines in a photograph will appear relatively straight and thus lack the extreme distortion that is characteristic of fisheye lenses. Rectilinear lenses are more versatile and can be used in architectural and landscape photography.
Currently Sigma makes two zoom lenses in the 10-20mm range. In this review, we'll examine the Sigma 10-20mm F/3.5 EX DC HSM and the Sigma 10-20mm F/4-5.6 EX DC J. Both lenses are ultra-wide angle reticular zooms for the Pentax system.
Review originally published on May 28th, 2012