The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Tamron 17-70 F2.8 Di III-A VC and the Sigma 30mm F1.4 C 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 17-70 F2.8 Di III-A VC is the longer of the two lenses at 119mm. The Sigma 30mm F1.4 C with a length of 73mm, is 46mm shorter. Besides being longer, the Tamron 17-70 F2.8 Di III-A VC also has a larger diameter of 75mm compared to the Sigma 30mm F1.4 C's 65mm diameter.
Below you can find a scaled side-by-side image of Tamron 17-70 F2.8 Di III-A VC and Sigma 30mm F1.4 C to get a better idea of how their sizes compare in real life.
Comparison image of the Tamron 17-70 F2.8 Di III-A VC and the Sigma 30mm F1.4 C Size and Weight 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 30mm F1.4 C weighs 265g, 49% (260g) lighter than the Tamron 17-70 F2.8 Di III-A VC's weight of 525g.
Filter Threads
The Tamron 17-70 F2.8 Di III-A VC has a filter size of 67mm whereas the Sigma 30mm F1.4 C 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 Tamron 17-70 F2.8 Di III-A VC:
And these are the 52mm filters that we recommend for the Sigma 30mm F1.4 C:
Lens Mounts
Both the Tamron 17-70 F2.8 Di III-A VC and the Sigma 30mm F1.4 C has the same Fujifilm X lens mount . Some of the latest released cameras that are compatible with the Fujifilm X lenses are Fujifilm X-T30 III , Fujifilm X-E5 and Fujifilm X-M5 .
Tamron 17-70 F2.8 Di III-A VC is also available in the Sony E mount.
Sigma 30mm F1.4 C is also available in Sony E , Micro Four Thirds , Nikon Z , Leica L and Canon RF mounts.
Focal Range
Tamron 17-70 F2.8 Di III-A VC has a focal range of 17-70mm and
4.1X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of
25.5-105mm when used on a APS-C / DX format camera.
On the other hand, the Sigma 30mm F1.4 C is a prime lens with fixed focal lenght of 30mm which has an effective (full-frame 35mm equivalent) focal range of 45mm when used on a APS-C / DX format camera.