The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Canon 85mm f1.8 USM and the Tamron 90mm F2.8 VC Macro 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. Tamron 90mm F2.8 VC Macro is the longer of the two lenses at 117mm. The Canon 85mm f1.8 USM with a length of 72mm, is 45mm shorter. Besides being longer, the Tamron 90mm F2.8 VC Macro also has a larger diameter of 79mm compared to the Canon 85mm f1.8 USM's 75mm 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 85mm f1.8 USM weighs 425g, which means it is 184g (30%) lighter than the Tamron 90mm F2.8 VC Macro which has a weight of 609g.
Filter Threads
The Canon 85mm f1.8 USM has a filter size of 58mm whereas the Tamron 90mm F2.8 VC Macro has a 62mm 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 85mm f1.8 USM:
And these are the 62mm filters that we recommend for the Tamron 90mm F2.8 VC Macro:
Lens Mounts
Both the Canon 85mm f1.8 USM and the Tamron 90mm F2.8 VC Macro 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 90mm F2.8 VC Macro is also available in Sony Alpha and Nikon F (FX) mounts.
Focal Range
Canon 85mm f1.8 USM 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.
On the other hand, the Tamron 90mm F2.8 VC Macro is a prime lens with fixed focal lenght of 90mm. When it is mounted on an APS-C sensor camera with 1.6x crop, it provides a 35mm (FF) equivalent of 144mm.