The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Tokina 16-50mm f2.8 DX and the Canon 28-135mm f3.5-5.6 IS USM for their suitability to various photography scenarios:
Size and Weight Comparison
The weight of a lens is as important as its external dimensions, especially if you are planning to hand hold your camera and lens combination for longer periods. Canon 28-135mm f3.5-5.6 IS USM weighs 540g, 11% (70g) lighter than the Tokina 16-50mm f2.8 DX's weight of 610g.
Below you can find the dimension and weight table of the Standard Zoom Lenses in Canon EF Mount for size comparison purposes.
Standard Zoom Lenses in Canon EF Mount for Size Comparison
Both the Tokina 16-50mm f2.8 DX and the Canon 28-135mm f3.5-5.6 IS USM 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.
Tokina 16-50mm f2.8 DX is also available in Nikon F (DX) mount.
Tokina 16-50mm f2.8 DX has a focal range of 16-50mm and 3.1X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of 25.6-80mm when used on a APS-C / DX format camera. Canon 28-135mm f3.5-5.6 IS USM has a focal range of 28-135mm and 4.8X zoom ratio . When it is mounted on an APS-C sensor camera with 1.6x crop, it provides a 35mm (FF) equivalent of 44.8 - 216mm.