The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Sony E 18-135mm F3.5-5.6 OSS and the Sigma 18-250mm F3.5-6.3 DC OS HSM for their suitability to various photography scenarios:
Size and Weight Comparison
The size of a lens is an important deciding factor when comparing two lenses. Sigma 18-250mm F3.5-6.3 DC OS HSM is the longer of the two lenses at 89mm. The Sony E 18-135mm F3.5-5.6 OSS with a length of 88mm, is 1mm shorter. Besides being longer, the Sigma 18-250mm F3.5-6.3 DC OS HSM also has a larger diameter of 74mm compared to the Sony E 18-135mm F3.5-5.6 OSS's 67mm diameter.
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. Sony E 18-135mm F3.5-5.6 OSS weighs 325g, which means it is 145g (30%) lighter than the Sigma 18-250mm F3.5-6.3 DC OS HSM which has a weight of 470g.
Lens Mounts
The Sony E 18-135mm F3.5-5.6 OSS has the Sony E lens mount whereas the Sigma 18-250mm F3.5-6.3 DC OS HSM has the Sony Alpha lens mount. Some of the latest released cameras that are compatible with these mounts are Sony FX30, Sony ZV-E10 and Sony A6600 for the Sony E Mount and Sony A68, Sony A77 II and Sony A58 for the Sony Alpha Mount.
Sigma 18-250mm F3.5-6.3 DC OS HSM is also available in Canon EF , Nikon F (DX), Pentax KAF3, Sigma SA, Canon EF, Nikon F (DX), Pentax KAF3, Sony Alpha and Sigma SA mounts.
Focal Range
Sony E 18-135mm F3.5-5.6 OSS has a focal range of 18-135mm and 7.5X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of 27-202.5mm when used on a APS-C / DX format camera. Sigma 18-250mm F3.5-6.3 DC OS HSM has a focal range of 18-250mm and 13.9X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of 27-375mm when used on a APS-C / DX format camera.