The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Sigma 24-105mm F4 DG OS HSM and the Sigma 18-35mm F1.8 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. Sigma 18-35mm F1.8 DC HSM is the longer of the two lenses at 121mm. The Sigma 24-105mm F4 DG OS HSM with a length of 109mm, is 12mm shorter. On the other hand, the Sigma 24-105mm F4 DG OS HSM has a larger diameter of 89mm compared to the Sigma 18-35mm F1.8 DC HSM's 78mm 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 18-35mm F1.8 DC HSM weighs 810g, 8% (75g) lighter than the Sigma 24-105mm F4 DG OS HSM's weight of 885g.
Below you can find the dimension and weight table of the Standard Zoom Lenses in Sony Alpha Mount for size comparison purposes.
Standard Lenses in Sony Alpha Mount for Size Comparison
Filter Threads
The Sigma 24-105mm F4 DG OS HSM has a filter size of 82mm whereas the Sigma 18-35mm F1.8 DC HSM has a 72mm diameter. Larger filters are generally more expensive than the smaller ones given all the other features are equal.
Below are links to the 82mm filters that we recommend you to consider for the Sigma 24-105mm F4 DG OS HSM:
And these are the 72mm filters that we recommend for the Sigma 18-35mm F1.8 DC HSM:
Lens Mounts
Both the Sigma 24-105mm F4 DG OS HSM and the Sigma 18-35mm F1.8 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.
Sigma 24-105mm F4 DG OS HSM is also available in Canon EF , Nikon F (FX) and Sigma SA mounts.
Sigma 18-35mm F1.8 DC HSM is also available in Canon EF , Pentax KAF, Sigma SA and Nikon F (DX) mounts.
Focal Range
Sigma 24-105mm F4 DG OS HSM has a focal range of 24-105mm and
4.4X zoom ratio . When it is mounted on an APS-C sensor camera with 1.5x crop, it provides a 35mm (FF) equivalent of
36 - 157.5mm.
On the other hand, the Sigma 18-35mm F1.8 DC HSM has a focal range of 18-35mm and 1.9X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of 27-52.5mm when used on a APS-C / DX format camera.