Tamron rewrote its web site. This was the occasion to move the Lens Comparison Tool but it is still useful to compare a 400mm with a 500mm (or a 35mm with a 50mm).
![tamron_lens_comparison_tool Tamron - Lens Comparison Tool (based on focal length)](https://ylovephoto.com/fr/wp-content/uploads/2009/05/tamron_lens_comparison_tool.png)
But you can also find a similar tool at Olympus (and it takes into account the specificities of 4/3 sensor format, of course): Perfect Lens finder.
![olympus_lens_comparison Olympus Perfect Lens Finder](https://ylovephoto.com/fr/wp-content/uploads/2009/05/olympus_lens_comparison.png)