I have only recently moved up to SLR photography and so please bear in mind that the following comments are not intended to provide a technical review of this product but, hopefully, they will be of assistance to others like myself taking this first step.
Earlier this year I purchased a Pentax K-R DSLR camera with the boxed 18-55mm lens having been impressed by the 6 fps which I felt was just right for my foray into sports photography. I have not been disappointed !
Having got to grips with the basics I turned my attention to a decent telephoto lens for those other-end-of-the-pitch rugby shots. Not wanting to spend a small fortune at this stage, I trawled the Amazon site and came across the Sigma 70-300mm f4-5.6 Macro DG Lens For Pentax Digital & Film SLR Cameras
which came with excellent reviews.
Although I have only had the lens for a short while and have not yet been able to use it for its primary purpose, the results so far have been excellent with quick auto-focusing and lovely sharp images - just as others have commented before me.
Needless to say, I am delighted with the product and would highly recommend it to anyone - like myself - starting out on the DSLR path.