One of the issues with Digital SLR camera is the narrowed angle of view. As most of such digital SLR cameras have the smaller size image sensor than film, it provides narrower angle image. You need to use the shorter focal length lens if you want take the same angle image as 35mm film SLR camera provides. For example, the digital SLR cameras with APS-C size image sensor such as CANON EOS10D Digital and Digital Rebel actually has 1.6-multiplier factor. So you need to use very short focal length like 10.5-22mm zoom lens to take an equivalent angle image of 17-35 mm zoom lens. However, the line-up of lenses for conventional SLR cameras does not have such short focus length lens except for the fisheye lens. If you really wanted to take a wide angle image with digital SLR camera, the only choice for you was to use 14mm fixed focal length lens.

12-24mm F4.5-5.6EX DG

But Sigma has now introduced 12-24mm F4.5-5.6 EX ASPHERICAL HSM, the innovative ultra-wide zoom lens. If you use this lens with digital SLR camera, the focal length becomes 19.2-38.4mm equivalent, which is wider angle than the one taken by 14 mm fixed focal length lens. You must be attracted by its budget price.

Although Nikon also has 12-24mm zoom lens, it is dedicated for digital SLR cameras with APS-C size image sensor. On the other hand, this Sigma lens covers 35mm film full size, which could be used both for digital SLR camera and 35mm film SLR camera. This is an advantage for Sigma because this Sigma lens can be used with all Canon digital SLR cameras, including 35mm size, APS-H size, and APS-C size. If the price of digital SLR cameras with the larger imager sensor (APS-H or 35mm full size) goes down and such camera becomes available for consumers, the lens can be used with such cameras.

When I bought Sigma 12-24mm F4.5-5.6 EX DG ASPHERICAL HSM, I had only APS-C sized digital SLR cameras such as EOS 10D Digital and Digital Rebel. However, after a few months later, CANON EOS-1D MarkII Digital with APS-H sized image sensor was released and I bought it on impulse. Thus, in the future, even if the advance of the technology will make us possible to get digital SLR cameras with APS-H or 35mm sized image sensors more inexpensively, Sigma 12-24mm F4.5-5.6 EX DG ASPHERICAL HSM which covers 35mm full size image sensor can be used with any type of digital SLR cameras.

Sigma 12-24mm F4.5-5.6 EX DG ASPHERICAL HSM attracts us with HSM lens drive. HSM can provide quiet high-speed auto focus, as well as full-time manual focus, which are comfortable for users.

This ultra-wide zoom lens makes it possible to have a fine image without blurring on the edge of frame in spite of its ultra wide angel of view. It’s quite amazing that such ultra wide angle zoom lens provides such a fine image quality. Another remarkable point of this lens is less distortion.

However, even if ultra wide angle lens has deeper depth of field, you need to be careful about the accurate focusing. Even with the slight out focus, it deteriorates the image sharpness in case of digital SLR cameras. In addition, since the AF sensor does not have the capability to detect the slight out focus at 12mm, you should use MF, not AF in case you take a picture of long distance landscapes.

This lens attracts us very much by its excellent ultra-zoom description. I appreciate that we can get such an excellent lens with an affordable price.