Size and Weight Comparison
Size of a lens is an important deciding factor when comparing two lenses.Sony 70-300mm F4.5-5.6 G SSM is the longer of the two lenses at 136mm. The Tamron AF 70-300mm f4-5.6 LD with a length of 117mm is 19mm shorter. Besides being longer, the Sony 70-300mm F4.5-5.6 G SSM also has a larger diameter of 83mm compared to Tamron AF 70-300mm f4-5.6 LD's 77mm diameter.
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. Tamron AF 70-300mm f4-5.6 LD weighs 435g, which means it is 325g (74%) lighter than the Sony 70-300mm F4.5-5.6 G SSM which has a weight of 760g.
Below you can find the dimension and weight table of the 'Telephoto Zoom Lenses in Sony Alpha Mount for size comparison purposes.
Telephoto Zoom Lenses in Sony Alpha Mount for Size Comparison
Both Tamron AF 70-300mm f4-5.6 LD and Sony 70-300mm F4.5-5.6 G SSM has the same Sony Alpha lens mount. Some of the latest released cameras that are compatible with the Sony Alpha lenses are Sony A99 II, Sony A68 and Sony A77 II.
Tamron AF 70-300mm f4-5.6 LD is also available in Canon EF , Nikon F (FX) and Pentax KAF mounts.