Flight Simulator and other chat
https://forums.simviation.com/phpBB3/
https://forums.simviation.com/phpBB3/viewtopic.php?f=40&t=121623
I'd go for the Canon, without question. You're much better off staying with lenses from the company your camera is from in my opinion. Have tried Sigma (not that one) equipment and wasn't impressed.

photographers always moan about Sigma, well most of them...?
I've got the same question, I'm looking for a good zoom lens to replace my Tamron 55-200.
It has to be compact so I can take it with me on holidays. I've got the Bigma (Sigma 50-500) for spotting but it's way to big and heavy to take it with me when I travel. I need it for spotting and general holiday pics. My camera is a Canon 350D.
How about this one?
http://www.pixmania.co.uk/uk/uk/155727/art/canon/ef-70-300mm-f-4-5-6-is-us.html
Any good or are there better ones in the same price range?
Thanks, Frank.