The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Sigma 65mm F2 DG DN and the Sigma 56mm F1.4 DC DN C 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 65mm F2 DG DN is the longer of the two lenses at 75mm. The Sigma 56mm F1.4 DC DN C with a length of 60mm, is 15mm shorter. Besides being longer, the Sigma 65mm F2 DG DN also has a larger diameter of 72mm compared to the Sigma 56mm F1.4 DC DN C's 67mm 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 56mm F1.4 DC DN C weighs 280g, 30% (125g) lighter than the Sigma 65mm F2 DG DN's weight of 405g.
Below you can find the dimension and weight table of the Standard Prime Lenses in Leica L Mount for size comparison purposes.
Standard Lenses in Leica L Mount for Size Comparison
Filter Threads
The Sigma 65mm F2 DG DN has a filter size of 62mm whereas the Sigma 56mm F1.4 DC DN C has a 55mm diameter. Larger filters are generally more expensive than the smaller ones given all the other features are equal.
Below are links to the 62mm filters that we recommend you to consider for the Sigma 65mm F2 DG DN:
And these are the 55mm filters that we recommend for the Sigma 56mm F1.4 DC DN C:
Lens Mounts
Both the Sigma 65mm F2 DG DN and the Sigma 56mm F1.4 DC DN C has the same Leica L lens mount. Some of the latest released cameras that are compatible with the Leica L lenses are Leica SL3, Panasonic S5 II and Panasonic S5 II X.
Sigma 65mm F2 DG DN is also available in Sony E mount.
Sigma 56mm F1.4 DC DN C is also available in Micro Four Thirds and Sony E mounts.
Focal Range
Sigma 65mm F2 DG DN is a prime lens with fixed focal lenght of 65mm.
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.