The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Sigma 90mm F2.8 DG DN C and the Sigma 56mm F1.4 DC DN C for their suitability to various photography scenarios:
Size and Weight Comparison
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 56mm F1.4 DC DN C weighs 280g, 5% (15g) lighter than the Sigma 90mm F2.8 DG DN C's weight of 295g.
Filter Threads
Both the Sigma 90mm F2.8 DG DN C and the Sigma 56mm F1.4 DC DN C have the same Filter thread size of 55mm.
Below are links to the 55mm filters that we recommend you to consider for these lenses:
Lens Mounts
The Sigma 90mm F2.8 DG DN C has the Sony E lens mount whereas the Sigma 56mm F1.4 DC DN C has the Leica L lens mount. Some of the latest released cameras that are compatible with these mounts are Sony FX5, Sony A7R VI and Sony A7 V for the Sony E Mount and Leica TL2, Leica TL and Leica T Typ 701 for the Leica L Mount.
Sigma 90mm F2.8 DG DN C is also available in the Leica L mount.
Sigma 56mm F1.4 DC DN C is also available in Micro Four Thirds and Sony E mounts.
Focal Range
Sigma 90mm F2.8 DG DN C is a prime lens with fixed focal lenght of 90mm.
On the other hand, the Sigma 56mm F1.4 DC DN C is a prime lens with fixed focal lenght of 56mm which has an effective (full-frame 35mm equivalent) focal range of 84mm when used on a APS-C / DX format camera.
