The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Sigma 50mm F1.4 EX DG HSM and the Sigma 17-70mm F2.8-4 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 17-70mm F2.8-4 DC OS HSM is the longer of the two lenses at 89mm. The Sigma 50mm F1.4 EX DG HSM with a length of 68mm, is 21mm shorter. On the other hand, the Sigma 50mm F1.4 EX DG HSM has a larger diameter of 85mm compared to the Sigma 17-70mm F2.8-4 DC OS HSM's 79mm 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 50mm F1.4 EX DG HSM weighs 505g, which means it is 15g (2%) lighter than the Sigma 17-70mm F2.8-4 DC OS HSM which has a weight of 520g.
Filter Threads
The Sigma 50mm F1.4 EX DG HSM has a filter size of 77mm whereas the Sigma 17-70mm F2.8-4 DC OS 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 77mm filters that we recommend you to consider for the Sigma 50mm F1.4 EX DG HSM:
And these are the 72mm filters that we recommend for the Sigma 17-70mm F2.8-4 DC OS HSM:
Lens Mounts
The Sigma 50mm F1.4 EX DG HSM has the Pentax KAF3 lens mount whereas the Sigma 17-70mm F2.8-4 DC OS HSM has the Sigma SA lens mount. Some of the latest released cameras that are compatible with these mounts are , and for the Pentax KAF3 Mount and Sigma SD1 Merrill, Sigma SD1 and for the Sigma SA Mount.
Sigma 50mm F1.4 EX DG HSM is also available in the Canon EF , Sony Alpha, Sigma SA, Nikon F (FX) and Four Thirds mounts.
Sigma 17-70mm F2.8-4 DC OS HSM is also available in Canon EF , Pentax KAF3, Sony Alpha and Nikon F (DX) mounts.
Focal Range
Sigma 50mm F1.4 EX DG HSM is a prime lens with fixed focal lenght of 50mm. When it is mounted on an APS-C sensor camera with 1.5x crop, it provides a 35mm (FF) equivalent of
75mm.
On the other hand, the Sigma 17-70mm F2.8-4 DC OS HSM 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.
