The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Canon 100mm f2.8 Macro USM and the Tamron 85mm F1.8 VC for their suitability to various photography scenarios:
Size and Weight Comparison
The size of a lens is a crucial factor to consider when comparing two lenses. Canon 100mm f2.8 Macro USM is the longer of the two lenses at 119mm. The Tamron 85mm F1.8 VC with a length of 91mm, is 28mm shorter. On the other hand, the Tamron 85mm F1.8 VC has a larger diameter of 85mm compared to the Canon 100mm f2.8 Macro USM's 79mm diameter.
The weight of a lens is equally significant as its external dimensions, particularly if you intend to handhold your camera and lens combination for extended periods. Canon 100mm f2.8 Macro USM weighs 600g, which means it is 100g (14%) lighter than the Tamron 85mm F1.8 VC which has a weight of 700g.
Filter Threads
The Canon 100mm f2.8 Macro USM has a filter size of 58mm whereas the Tamron 85mm F1.8 VC has a 67mm diameter. Larger filters are generally more expensive than the smaller ones given all the other features are equal.
Below are links to the 58mm filters that we recommend you to consider for the Canon 100mm f2.8 Macro USM:
And these are the 67mm filters that we recommend for the Tamron 85mm F1.8 VC:
Lens Mounts
Both the Canon 100mm f2.8 Macro USM and the Tamron 85mm F1.8 VC has the same Canon EF lens mount. Some of the latest released cameras that are compatible with the Canon EF lenses are Canon 1D X III, Canon 6D MII and Canon 5D MIV.
Tamron 85mm F1.8 VC is also available in Sony Alpha and Nikon F (FX) mounts.
Focal Range
Canon 100mm f2.8 Macro USM is a prime lens with fixed focal lenght of 100mm. When it is mounted on an APS-C sensor camera with 1.6x crop, it provides a 35mm (FF) equivalent of
160mm.
On the other hand, the Tamron 85mm F1.8 VC is a prime lens with fixed focal lenght of 85mm. When it is mounted on an APS-C sensor camera with 1.6x crop, it provides a 35mm (FF) equivalent of 136mm.