The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Sigma 18-50mm F2.8-4.5 DC OS HSM and the Nikon 18-55mm f3.5-5.6G VR 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. Sigma 18-50mm F2.8-4.5 DC OS HSM is the longer of the two lenses at 89mm. The Nikon 18-55mm f3.5-5.6G VR with a length of 80mm, is 9mm shorter. Besides being longer, the Sigma 18-50mm F2.8-4.5 DC OS HSM also has a larger diameter of 74mm compared to the Nikon 18-55mm f3.5-5.6G VR's 73mm 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. Nikon 18-55mm f3.5-5.6G VR weighs 265g, 32% (130g) lighter than the Sigma 18-50mm F2.8-4.5 DC OS HSM's weight of 395g.
Filter Threads
The Sigma 18-50mm F2.8-4.5 DC OS HSM has a filter size of 67mm whereas the Nikon 18-55mm f3.5-5.6G VR has a 52mm 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 Sigma 18-50mm F2.8-4.5 DC OS HSM:
And these are the 52mm filters that we recommend for the Nikon 18-55mm f3.5-5.6G VR:
Lens Mounts
Both the Sigma 18-50mm F2.8-4.5 DC OS HSM and the Nikon 18-55mm f3.5-5.6G VR has the same Nikon F (DX) lens mount. Some of the latest released cameras that are compatible with the Nikon F (DX) lenses are Nikon D3500, Nikon D7500 and Nikon D5600.
Sigma 18-50mm F2.8-4.5 DC OS HSM is also available in Canon EF , Pentax KAF3, Sony Alpha and Sigma SA mounts.
Nikon 18-55mm f3.5-5.6G VR is also available in Nikon F (DX) mount.
Focal Range
Sigma 18-50mm F2.8-4.5 DC OS HSM has a focal range of 18-50mm and
2.8X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of
27-75mm when used on a APS-C / DX format camera.
On the other hand, the Nikon 18-55mm f3.5-5.6G VR has a focal range of 18-55mm and 3.1X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of 27-82.5mm when used on a APS-C / DX format camera.