The Canon EF 24-70mm f/2.8L lens was developed as a replacement for the famed 28-70 f/2.8 which became a staple for photographers who wanted to match the image quality of prime lenses with a more versatile zoom lens. Essentially, the 24-70mm is designed to replace an entire range of three fixed focal length lenses by offering identical image quality with the added benefit of versatility.
To improve upon the older 28-70, Canon redesigned the glass elements of the lens, added a new auto-focus processor to improve focus speed and accuracy, and sealed the lens to protect from dust and moisture damage. When used with a Canon 1V, 1D or 1Ds, the 24-70mm forms a dust proof and water tight seal with the camera. Ultimately, the 24-70mm comes close, but fails to match the image quality of professional level prime lenses.
The Canon 24-70 f/2.8L has been considered the general purpose walk around lens for Canon SLR users. An extremely popular standard zoom lens for both the professional and the serious amateur, its focal length is versatile, its maximum aperture of 2.8 is fast, its images are pleasing, and the build quality is solid. It is my “go-to” zoom lens for weddings, as it can handle a wide group shot, and can just as easily zoom in for a tighter portrait.
Specifications
- Focal length : 24-70mm
- Maximum aperture : 1:2.8
- Lens construction : 16 elements in 13 groups
- Diagonal angle of view : 74 to 29 degrees
- Focus adjustment : Front-focusing method
- Closest focusing distance : 1.25 feet
- Zoom system : Rotating type
- Filter size : 77mm
- Dimensions : 3.3 inches in diameter, 4.9 inches long
- Weight : 2.1 pounds
Source : http://www.digitalphotographygear.com