The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Pentax D-FA 50mm F2.8 Macro and the Pentax 40mm F2.8 XS Lens 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. Pentax D-FA 50mm F2.8 Macro is the longer of the two lenses at 60mm. The Pentax 40mm F2.8 XS Lens with a length of 9mm, is 51mm shorter. Besides being longer, the Pentax D-FA 50mm F2.8 Macro also has a larger diameter of 68mm compared to the Pentax 40mm F2.8 XS Lens's 63mm 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 40mm F2.8 XS Lens weighs 45g, 83% (220g) lighter than the Pentax D-FA 50mm F2.8 Macro's weight of 265g.
Lens Mounts
Both the Pentax D-FA 50mm F2.8 Macro and the Pentax 40mm F2.8 XS Lens 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.
Focal Range
Pentax D-FA 50mm F2.8 Macro 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 Pentax 40mm F2.8 XS Lens is a prime lens with fixed focal lenght of 40mm which has an effective (full-frame 35mm equivalent) focal range of 60mm when used on a APS-C / DX format camera.