The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Venus 105mm F2 and the Canon 300mm f4.0L IS 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 300mm f4.0L IS USM is the longer of the two lenses at 221mm. The Venus 105mm F2 with a length of 99mm, is 122mm shorter. Besides being longer, the Canon 300mm f4.0L IS USM also has a larger diameter of 90mm compared to the Venus 105mm F2's 76mm 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. Venus 105mm F2 weighs 745g, which means it is 445g (37%) lighter than the Canon 300mm f4.0L IS USM which has a weight of 1190g.
Below you can find the dimension and weight table of the Telephoto Prime Lenses in Canon EF Mount for size comparison purposes.
Telephoto Lenses in Canon EF Mount for Size Comparison
Filter Threads
The Venus 105mm F2 has a filter size of 67mm whereas the Canon 300mm f4.0L IS USM has a 77mm diameter. Larger filters are generally more expensive than the smaller ones given all the other features are equal.
Below are links to the 67mm filters that we recommend you to consider for the Venus 105mm F2:
And these are the 77mm filters that we recommend for the Canon 300mm f4.0L IS USM:
Lens Mounts
Both the Venus 105mm F2 and the Canon 300mm f4.0L IS USM has the same Canon EF lens mount. Some of the latest released cameras that are compatible with the Canon EF lenses are Blackmagic URSA 12K LF, Z CAM E2-F6 II 6K and Z CAM E2-S6 II 6K.
Venus 105mm F2 is also available in the Sony E , Nikon F (FX), Pentax KAF2 and Sony Alpha mounts.
Focal Range
Venus 105mm F2 is a prime lens with fixed focal lenght of 105mm. When it is mounted on an APS-C sensor camera with 1.6x crop, it provides a 35mm (FF) equivalent of
168mm.
On the other hand, the Canon 300mm f4.0L IS USM is a prime lens with fixed focal lenght of 300mm. When it is mounted on an APS-C sensor camera with 1.6x crop, it provides a 35mm (FF) equivalent of 480mm.