The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Tamron AF 28-300mm f3.5-6.3 XR LD and the Sigma 18-50mm F2.8-4.5 DC OS HSM 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 Tamron AF 28-300mm f3.5-6.3 XR LD with a length of 84mm, is 5mm 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 Tamron AF 28-300mm f3.5-6.3 XR LD'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. Sigma 18-50mm F2.8-4.5 DC OS HSM weighs 395g, 5% (25g) lighter than the Tamron AF 28-300mm f3.5-6.3 XR LD's weight of 420g.
Filter Threads
The Tamron AF 28-300mm f3.5-6.3 XR LD has a filter size of 62mm whereas the Sigma 18-50mm F2.8-4.5 DC OS HSM has a 67mm diameter. Larger filters are generally more expensive than the smaller ones given all the other features are equal.
Below are links to the 62mm filters that we recommend you to consider for the Tamron AF 28-300mm f3.5-6.3 XR LD:
And these are the 67mm filters that we recommend for the Sigma 18-50mm F2.8-4.5 DC OS HSM:
Lens Mounts
The Tamron AF 28-300mm f3.5-6.3 XR LD has the Nikon F (FX) lens mount whereas the Sigma 18-50mm F2.8-4.5 DC OS HSM has the Nikon F (DX) lens mount. Some of the latest released cameras that are compatible with these mounts are Nikon D6, Nikon D780 and Nikon D3500 for the Nikon F (FX) Mount and Nikon D3500, Nikon D7500 and Nikon D5600 for the Nikon F (DX) Mount.
Tamron AF 28-300mm f3.5-6.3 XR LD is also available in the Canon EF , Sony Alpha and Pentax KAF mounts.
Sigma 18-50mm F2.8-4.5 DC OS HSM is also available in Canon EF , Pentax KAF3, Sony Alpha and Sigma SA mounts.
Focal Range
Tamron AF 28-300mm f3.5-6.3 XR LD has a focal range of 28-300mm and
10.7X zoom ratio . When it is mounted on an APS-C sensor camera with 1.5x crop, it provides a 35mm (FF) equivalent of
42 - 450mm.
On the other hand, the 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.
