The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Sigma 50-100mm F1.8 A and the Tokina 50-135mm f2.8 DX 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. Sigma 50-100mm F1.8 A is the longer of the two lenses at 171mm. The Tokina 50-135mm f2.8 DX with a length of 135mm, is 36mm shorter. Besides being longer, the Sigma 50-100mm F1.8 A also has a larger diameter of 94mm compared to the Tokina 50-135mm f2.8 DX's 78mm 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. Tokina 50-135mm f2.8 DX weighs 845g, 43% (645g) lighter than the Sigma 50-100mm F1.8 A's weight of 1490g.
Below you can find the dimension and weight table of the Telephoto Zoom Lenses in Canon EF Mount for size comparison purposes.
Telephoto Lenses in Canon EF Mount for Size Comparison
Filter Threads
The Sigma 50-100mm F1.8 A has a filter size of 82mm whereas the Tokina 50-135mm f2.8 DX 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 82mm filters that we recommend you to consider for the Sigma 50-100mm F1.8 A:
And these are the 67mm filters that we recommend for the Tokina 50-135mm f2.8 DX:
Lens Mounts
Both the Sigma 50-100mm F1.8 A and the Tokina 50-135mm f2.8 DX has the same Canon EF lens mount. Some of the latest released cameras that are compatible with the Canon EF lenses are Canon T8i, Canon 90D and Canon SL3.
Sigma 50-100mm F1.8 A is also available in Nikon F (DX) and Sigma SA mounts.
Tokina 50-135mm f2.8 DX is also available in Nikon F (DX) mount.
Focal Range
Sigma 50-100mm F1.8 A has a focal range of 50-100mm and
2.0X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of
80-160mm when used on a APS-C / DX format camera.
On the other hand, the Tokina 50-135mm f2.8 DX has a focal range of 50-135mm and 2.7X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of 80-216mm when used on a APS-C / DX format camera.