The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Sigma 40mm F1.4 DG HSM A and the Sigma 17-50mm F2.8 EX 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 40mm F1.4 DG HSM A is the longer of the two lenses at 131mm. The Sigma 17-50mm F2.8 EX DC OS HSM with a length of 92mm, is 39mm shorter. Besides being longer, the Sigma 40mm F1.4 DG HSM A also has a larger diameter of 88mm compared to the Sigma 17-50mm F2.8 EX DC OS HSM's 84mm 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 17-50mm F2.8 EX DC OS HSM weighs 565g, 52% (635g) lighter than the Sigma 40mm F1.4 DG HSM A's weight of 1200g.
Filter Threads
The Sigma 40mm F1.4 DG HSM A has a filter size of 82mm whereas the Sigma 17-50mm F2.8 EX DC OS HSM has a 77mm 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 40mm F1.4 DG HSM A:
And these are the 77mm filters that we recommend for the Sigma 17-50mm F2.8 EX DC OS HSM:
Lens Mounts
Both the Sigma 40mm F1.4 DG HSM A and the Sigma 17-50mm F2.8 EX DC OS HSM has the same Sigma SA lens mount. Some of the latest released cameras that are compatible with the Sigma SA lenses are Sigma Quattro, Sigma Quattro H and Sigma SD1 Merrill.
Sigma 40mm F1.4 DG HSM A is also available in the Canon EF , Nikon F (FX), Sony E and Leica L mounts.
Sigma 17-50mm F2.8 EX DC OS HSM is also available in Canon EF , Pentax KAF3, Sony Alpha and Nikon F (DX) mounts.
Focal Range
Sigma 40mm F1.4 DG HSM A is a prime lens with fixed focal lenght of 40mm.
On the other hand, the Sigma 17-50mm F2.8 EX DC OS HSM has a focal range of 17-50mm and 2.9X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of 25.5-75mm when used on a APS-C / DX format camera.
