The type of photography that you are planning to use is an important decision factor. Here we have evaluated the HD Pentax-D FA 50mm F1.4 SDM AW and the Pentax DA 55mm F1.4 SDM for their suitability to various photography scenarios:
Size and Weight Comparison
Size of a lens is an important deciding factor when comparing two lenses.HD Pentax-D FA 50mm F1.4 SDM AW is the longer of the two lenses at 106mm. The Pentax DA 55mm F1.4 SDM with a length of 66mm is 40mm shorter. Besides being longer, the HD Pentax-D FA 50mm F1.4 SDM AW also has a larger diameter of 80mm compared to Pentax DA 55mm F1.4 SDM's 70mm diameter.
Weight of a lens is as important as its external dimensions, especially if you are planning to hand hold your camera and lens combination for longer periods. Pentax DA 55mm F1.4 SDM weighs 375g, 58% (535g) lighter than the HD Pentax-D FA 50mm F1.4 SDM AW's weight of 910g.
Below you can find the dimension and weight table of the 'Standard Prime Lenses in Pentax KAF3 Mount for size comparison purposes.
Standard Prime Lenses in Pentax KAF3 Mount for Size Comparison
Lens Mounts
Both HD Pentax-D FA 50mm F1.4 SDM AW and Pentax DA 55mm F1.4 SDM has the same Pentax KAF3 lens mount. Some of the latest released cameras that are compatible with the Pentax KAF3 lenses are Pentax KF, Pentax K-3 III and Pentax K-1 II.
Focal Range
HD Pentax-D FA 50mm F1.4 SDM AW 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 an 35mm (FF) equivalent of 75mm.
Pentax DA 55mm F1.4 SDM is a prime lens with fixed focal lenght of 55mm which has an effective (full-frame 35mm equivalent) focal range of 82.5mm when used on a APS-C / DX format camera.