The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Sigma 105mm F2.8 EX DG Macro and the Pentax D-FA 100mm F2.8 Macro WR 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 105mm F2.8 EX DG Macro is the longer of the two lenses at 98mm. The Pentax D-FA 100mm F2.8 Macro WR with a length of 81mm, is 17mm shorter. Besides being longer, the Sigma 105mm F2.8 EX DG Macro also has a larger diameter of 74mm compared to the Pentax D-FA 100mm F2.8 Macro WR's 65mm 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. Pentax D-FA 100mm F2.8 Macro WR weighs 340g, 26% (120g) lighter than the Sigma 105mm F2.8 EX DG Macro's weight of 460g.
Below you can find the dimension and weight table of the Macro Prime Lenses in Pentax KAF Mount for size comparison purposes.
Macro Lenses in Pentax KAF Mount for Size Comparison
Filter Threads
The Sigma 105mm F2.8 EX DG Macro has a filter size of 62mm whereas the Pentax D-FA 100mm F2.8 Macro WR has a 49mm 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 105mm F2.8 EX DG Macro:
And these are the 49mm filters that we recommend for the Pentax D-FA 100mm F2.8 Macro WR:
Lens Mounts
Both the Sigma 105mm F2.8 EX DG Macro and the Pentax D-FA 100mm F2.8 Macro WR has the same Pentax KAF lens mount. Some of the latest released cameras that are compatible with the Pentax KAF lenses are Pentax K-3 III Monochrome, Pentax KF and Pentax K-3 III.
Sigma 105mm F2.8 EX DG Macro is also available in Canon EF , Nikon F (FX), Sony Alpha, Sigma SA and Four Thirds mounts.
Focal Range
Sigma 105mm F2.8 EX DG Macro is a prime lens with fixed focal lenght of 105mm. When it is mounted on an APS-C sensor camera with 1.5x crop, it provides a 35mm (FF) equivalent of
157.5mm.
On the other hand, the Pentax D-FA 100mm F2.8 Macro WR is a prime lens with fixed focal lenght of 100mm. When it is mounted on an APS-C sensor camera with 1.5x crop, it provides a 35mm (FF) equivalent of 150mm.