SIGMA 28-70mm DF EX

I am hoping I have made right choice. I have scored a contract to shoot for rugby cards. The shots will be staged up close. I figure that my pentax will be not so forgiving; however I have come to know camera and its short falls. Pre focus and anticipation. I chose this lens above the DG as it will work on my film cams.
I will be shooting under oval lighting plus portable strobes. I do realize that with crop factor this will be around 42-105mm. I like my 28-70 2.8-4 UC and seem to gravitate to that lens a lot.
Any advice will be great I am still a noob with cameras and always will be. Something to be learnt every day.