The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Sigma 18-300 F3.5-6.3 DC OS HSM and the Canon 75-300mm f4.0-5.6 III USM 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 75-300mm f4.0-5.6 III USM is the longer of the two lenses at 122mm. The Sigma 18-300 F3.5-6.3 DC OS HSM with a length of 102mm, is 20mm shorter. On the other hand, the Sigma 18-300 F3.5-6.3 DC OS HSM has a larger diameter of 79mm compared to the Canon 75-300mm f4.0-5.6 III USM's 71mm 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 75-300mm f4.0-5.6 III USM weighs 480g, 17% (105g) lighter than the Sigma 18-300 F3.5-6.3 DC OS HSM's weight of 585g.
Filter Threads
The Sigma 18-300 F3.5-6.3 DC OS HSM has a filter size of 72mm whereas the Canon 75-300mm f4.0-5.6 III USM has a 58mm diameter. Larger filters are generally more expensive than the smaller ones given all the other features are equal.
Below are links to the 72mm filters that we recommend you to consider for the Sigma 18-300 F3.5-6.3 DC OS HSM:
And these are the 58mm filters that we recommend for the Canon 75-300mm f4.0-5.6 III USM:
Lens Mounts
The Sigma 18-300 F3.5-6.3 DC OS HSM has the Sony Alpha lens mount whereas the Canon 75-300mm f4.0-5.6 III USM has the Canon EF lens mount. Some of the latest released cameras that are compatible with these mounts are Sony A68, Sony A77 II and Sony A58 for the Sony Alpha Mount and Blackmagic URSA 12K LF, Z CAM E2-F6 II 6K and Z CAM E2-S6 II 6K for the Canon EF Mount.
Sigma 18-300 F3.5-6.3 DC OS HSM is also available in the Canon EF , Nikon F (DX), Pentax KAF3 and Sigma SA mounts.
Focal Range
Sigma 18-300 F3.5-6.3 DC OS HSM has a focal range of 18-300mm and
16.7X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of
27-450mm when used on a APS-C / DX format camera.
On the other hand, the Canon 75-300mm f4.0-5.6 III USM has a focal range of 75-300mm and 4.0X zoom ratio . When it is mounted on an APS-C sensor camera with 1.6x crop, it provides a 35mm (FF) equivalent of 120 - 480mm.
