The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Canon EF 600mm F4L IS III 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 EF 600mm F4L IS III USM is the longer of the two lenses at 448mm. The Tamron 85mm F1.8 VC with a length of 91mm, is 357mm shorter. Besides being longer, the Canon EF 600mm F4L IS III USM also has a larger diameter of 168mm compared to the Tamron 85mm F1.8 VC's 85mm 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. Tamron 85mm F1.8 VC weighs 700g, 77% (2350g) lighter than the Canon EF 600mm F4L IS III USM's weight of 3050g.
Filter Threads
The Canon EF 600mm F4L IS III USM has a filter size of 52mm 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 52mm filters that we recommend you to consider for the Canon EF 600mm F4L IS III USM:
And these are the 67mm filters that we recommend for the Tamron 85mm F1.8 VC:
Lens Mounts
Both the Canon EF 600mm F4L IS III 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 EF 600mm F4L IS III USM is a prime lens with fixed focal lenght of 600mm. When it is mounted on an APS-C sensor camera with 1.6x crop, it provides a 35mm (FF) equivalent of
960mm.
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.