The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Tamron 28-300mm f3.5-6.3 VC PZD and the Sigma 18-125mm F3.8-5.6 DC 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. Tamron 28-300mm f3.5-6.3 VC PZD is the longer of the two lenses at 96mm. The Sigma 18-125mm F3.8-5.6 DC HSM with a length of 89mm, is 7mm shorter. On the other hand, there is no difference between the max diameters of these lenses, both coming at 74mm.
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 18-125mm F3.8-5.6 DC HSM weighs 490g, 9% (50g) lighter than the Tamron 28-300mm f3.5-6.3 VC PZD's weight of 540g.
Below you can find the dimension and weight table of the SuperZoom Lenses in Sony Alpha Mount for size comparison purposes.
Superzoom Lenses in Sony Alpha Mount for Size Comparison
Filter Threads
The Tamron 28-300mm f3.5-6.3 VC PZD has a filter size of 67mm whereas the Sigma 18-125mm F3.8-5.6 DC HSM has a 62mm 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 Tamron 28-300mm f3.5-6.3 VC PZD:
And these are the 62mm filters that we recommend for the Sigma 18-125mm F3.8-5.6 DC HSM:
Lens Mounts
Both the Tamron 28-300mm f3.5-6.3 VC PZD and the Sigma 18-125mm F3.8-5.6 DC HSM 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 28-300mm f3.5-6.3 VC PZD is also available in the Canon EF and Nikon F (FX) mounts.
Sigma 18-125mm F3.8-5.6 DC HSM is also available in Pentax KAF3 mount.
Focal Range
Tamron 28-300mm f3.5-6.3 VC PZD 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 18-125mm F3.8-5.6 DC HSM has a focal range of 18-125mm and 6.9X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of 27-187.5mm when used on a APS-C / DX format camera.
