The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Sigma 10-20mm F4-5.6 EX DC HSM and the Tamron 10-24mm f3.5-4.5 II LD 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 10-24mm f3.5-4.5 II LD is the longer of the two lenses at 84mm. The Sigma 10-20mm F4-5.6 EX DC HSM with a length of 81mm, is 3mm shorter. On the other hand, the Sigma 10-20mm F4-5.6 EX DC HSM has a larger diameter of 84mm compared to the Tamron 10-24mm f3.5-4.5 II LD's 83mm 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. Tamron 10-24mm f3.5-4.5 II LD weighs 406g, 13% (64g) lighter than the Sigma 10-20mm F4-5.6 EX DC HSM's weight of 470g.
Below you can find the dimension and weight table of the Wideangle Zoom Lenses in Pentax KAF Mount for size comparison purposes.
Ultra-Wideangle Lenses in Pentax KAF Mount for Size Comparison
Filter Threads
Both the Sigma 10-20mm F4-5.6 EX DC HSM and the Tamron 10-24mm f3.5-4.5 II LD have the same Filter thread size of 77mm.
Below are links to the 77mm filters that we recommend you to consider for these lenses:
Lens Mounts
Both the Sigma 10-20mm F4-5.6 EX DC HSM and the Tamron 10-24mm f3.5-4.5 II LD has the same Pentax KAF lens mount. Some of the latest released cameras that are compatible with the Pentax KAF lenses are Pentax K-3 III Monochrome, Pentax KF and Pentax K-3 III.
Sigma 10-20mm F4-5.6 EX DC HSM is also available in Canon EF , Four Thirds, Sony Alpha, Sigma SA and Nikon F (DX) mounts.
Tamron 10-24mm f3.5-4.5 II LD is also available in Canon EF , Nikon F (DX), Sony Alpha and Canon EF mounts.
Focal Range
Sigma 10-20mm F4-5.6 EX DC HSM has a focal range of 10-20mm and
2.0X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of
15-30mm when used on a APS-C / DX format camera.
On the other hand, the Tamron 10-24mm f3.5-4.5 II LD has a focal range of 10-24mm and 2.4X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of 15-36mm when used on a APS-C / DX format camera.