Sigma's new 28-70mm f\/2.8 lens is exactly what you've come to expect from them. Even though the lens is squeezed into a compact size, there's no compromise on image quality and aperture. The manufacturer promises that the new 28-70mm lens is on par with the 24-70mm Art series glass in terms of image quality. Sure, the 4mm has been taken out of the wider end, but in rare situations shooting with it will be limited.<\/p>\n
So it's anything but a cheap budget lens for the photographer. Sigma has wanted to bring a lighter alternative to the Art series for mirrorless shooters. Although not an Art series lens, the mechanical quality has been maintained at a very high level, typical of Sigma. Indeed, the manufacturer's promise is that the stepper motor of the lens' focusing element is quiet and the autofocus is responsive.<\/p>\n
In terms of size, this has managed to keep the size of the equivalent f\/4 glass from most manufacturers. With minor adjustments, such as taking out a few elements and replacing them with special lenses, and changing the focal length from 24mm wide angle to 28mm, the lens size is more reasonable and half the weight is achieved (the angle of view is 75 degrees here and 85 degrees on the Art series glass). The lens uses the new Nano Porous Coating, which of course is also found on the new Art series glass.<\/p>\n
The body of the Sigma 28-70mm f\/2.8 is made from TSC (Thermally Stable Composite). Although the body material has achieved a considerable weight saving, the material does not change when going from cold to warm and the lens elements remain in place.<\/p>\n
The new Sigma has no mechanical lock and the AF Lock button has been removed from the lens. In terms of weather protection, the 24-70mm Art has better protection, but of course the 28-70mm is protected on the bayonet side and basic gaskets are found in the necessary places.<\/p>\n