Sigma, Tamron or Canon

Hi. I just bought the 30D and I'm concerned about what lens I need to buy. I have the Sigma 24-135 2.8-4.5 which I love. I mainly do portrait work but I want to experiment more. I want to get a good macro and zoom. The new Tamron 18-250mm came out a week ago but I'm not seeing reviews about it. The canon L series is great but to begin experimenting--I don't want to spend that much..I like Sigma and for work I have a Tamron. Also, I read contradictory info. about which lens company is best but I like the Sigma. Is there a HUGE difference from them to Canon? Thanks

The Canon L lenses will be very expensive but probably the best performers. Do not dismiss the more expensive Tamron and Sigma lenses as they can also be excellent lenses.

All manufacturers have different levels of lens quality and these can generally be recognised by the different price levels. If you want quality then also a more modest zoom range will have better potential. An 18-250mm lens might sound like a great idea, but it will be a series of compromises optically, will have relatively small apertures and/or may well be very bulky.

I am actually a Pentax user and I only buy proper Pentax lenses. If I were a Canon user i have no doubt that I would equally well stick to Canon lenses.