Digital BW, The Print

I have been giving Kodak Portra chromogenic B&W film scanned with a 
Nikon 4000ED a try but the images seem just a hair soft. Whether 
this is the film or the lens I don't know (Canon 24-85mm) but I 
suspect the lens. From previous experience I know the L glass is 
superb but it is a hair beyond my means at the moment. I used Tokina 
ATX in the past (bad mistake) and they had horrid flare problems. A 
friend suggested the new Sigma EX series, particularly the 70-200. 
Has anyone had any experience with this lens?

Thanks

Roger