The Tamron 28-200mm f/2.8-5.6 Di III RXD predates the Sigma 20-200mm by five years. The Tamron has a slightly faster aperture ...
This is a macro lens with a difference, as it can also make a great telephoto lens for outdoor nature and landscape shots ...
Crop factor is an unnecessary complication for beginner photographers – just put the equivalent focal length on the lens ...