I remember being engaged in discussions on various photography-forums years ago focusing on the question of why there are no zooms out there faster than f/2.8. The design was said to be too complicated and expensive. Some were even of the opinion that a lens like this would be far too big and heavy to make any sense. And now, the Japanese demonstrate with the 18-35mm f/1.8 that it is possible, after all.
Sigma did not stop at f/2, but rather made the zoom even faster, which practically renders carrying of various primes (20/1.8, 35/1.8 etc.) redundant. Needless to say, that is only the case if the image quality of the new zoom is similarly good.
An aspect that needs to be taken into consideration with the new Sigma is related to the question of format: in days of efficient APS-C-sensors, one has to seriously ponder on whether or not to venture the step towards full frame and expensive optics.
The novel Sigma-zoom shows that it is possible to have more light intensity with similar DoF, less weight and smaller measurements (camera including lens, that is).
I can hardly wait to get to know more on the image performance and the price and if I am pleased with it, I’ll be happy to give the fastest zoom in the world a go on my SD1.