canon zoom

I know that there was a post on here talking about this before, but despite using the search engine, I can't find it. I am looking to buy a short zoom and top of my list would probably be the canon 24-105L IS. Sadly I cannot justify the expense, although I am trying believe me. It seems that canon list some more affordable ones without the L suffix. Is the quality difference really that great? Any other suggestions for cheaper lenses that would be worth a look at. Is the IS worth having at this sort of length, given that it will be used outdoors and low light probably won't be such an issue? Are there any Sigma alternatives?
Any help and advice would be, as always, greatly appreciated.
Eric

A cheaper alternative is the Tamron 28-75mm f2.8. I had one for a while and thought the image quality was very good. I believe David Clapp also used to use one, so perhaps he'll let you have his opinion if he sees this.

The Tamron gets excellent reviews, with some saying it matches the Canon equivalents (i.e. 24-70mm f2.8mm and 24-105mm) for image quality. I havn't done any back to back tests but it wouldn't be a million miles away, optically.

I have been using a Sigma 24-70mm f2.8 since its introduction in I think 2000 (or maybe 1999, anyway long before Canon brought out theirs.) and I reckon its a fantastic lens. I believe it has been updated now and I wouldn't hesitate in recommending it.

Eric, I too have the Tamron 28-75, and can confirm that it is a fine lens, especially considering the cost. However, if you're used to having USM, you'll need to get some earplugs - I think this is Tamron's Achilles' heel.

Regards,

Des

Thanks for the replies chaps. Food for thought there. At least I have some options now.
cheers.