Hey guys, About to branch out into portrait work. I already do a limited amount of event/commission work, and until now a combination of 28-135 IS and the Nifty Fifty has got me by. However, I've reached a point where I feel investing in some glass better suited to portrait (and wedding) jobs is a less of a good idea, and more of a requirement. Ideally, I'd quite like a mid-range zoom over a prime, so as it can also double as a walkabout lens for day to day work on my 50D and 350D backup. So far I've shortlisted (in ascending order): -Sigma 24-70 f/2.8 -Sigma 24-70 HSM f/2.8 -Canon 24-105 L f/4 Sadly, the 24-70L f/2.8 is out of my reach, and really the 24-105 is pushing it - though the f/2.8 Sigma offerings are better suited to the job in hand anyway. I guess my question should really be 1. is the more expensive 24-70 worth the extra ~£300? and 2. Alternatives?! Cheers in advance.