Forgive if this has been discussed before but I couldn't find any references to it. Looking at these two lenses it appears that the Tamron has several advantages over the Canon.
1. Better image quality ( according to latest Pop photograhy review )
2. Faster - brighter viewfinder image
3. Slightly longer working distance at 1:1
4. Can use it with a full frame camera as well by adding a 1.4 teleconverter. That should make a very decent 84mm F2.8 macro lens on a full frame camera and will probably do more than 1:1 ( Haven't been able to verify this)
Disavantage: $569 vs $400 for Canon.
Any thoughts? Has anybody tried it yet??