Richard Harris of Photo.net has published an excellent article comparing the Canon 100mm Macro USM lens and the Tamron 90mm Macro lens, in conjunction with the Canon EOS 10D DSLR. There are lots of sample photographs so that you can judge for yourself which is the best lens - the result might just surprise you…

“Due to the fact that in many (but not all) markets the Tamron 90mm Macro is substantially cheaper than the Canon 100mm Macro USM the question as to how the two lenses compare seems to crop up extremely often on the photo.net boards. What?s more, as an owner of the third party offering I have often wondered how it compares to the Canon lens. Like many others before me I have occasionally toyed with the idea of upgrading one day, however instead I decided to rent the Canon lens and do a side by side comparison.”

Website: Photo.net - Macro Lens Review