
Originally Posted by
Robert O'Toole
Thanks for the info.
Yes I agree about your comments on the Sigma lenses.
I want to add that the Canon lens is about $1300 at most shops, the Sigma is about $660, thats about a 50% premium.
The Canon 180 is capable of making great images no doubt but I used maybe 5 copies of the Canon 180 and owned one and I have to say that I found that the Sigma 150 had better IQ. The Canon 180 isnt really know to be a class IQ leader. Photozone made a comment that some Zooms have tested higher resolution.
You can actually use Canon extenders on the Sigma but you will have to use an extension tube and you will lose AF.
After owning Tamron 180, Sigma 180, and Canon 180, I would say that Canon AF is quicker but it makes large corrections and not always in the right direction. The 3rd party lenses AF slower, some like the Tamron much slower, but they also AF in smaller steps. This can be helpful when trying to AF on flying bees at close distances.
Just my opinion your mileage my vary :)
Robert