The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Pentax FA 50mm F1.4 Classic and the Pentax DA 55mm F1.4 SDM 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 DA 55mm F1.4 SDM is the longer of the two lenses at 66mm. The Pentax FA 50mm F1.4 Classic with a length of 37mm, is 29mm shorter. Besides being longer, the Pentax DA 55mm F1.4 SDM also has a larger diameter of 70mm compared to the Pentax FA 50mm F1.4 Classic'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 FA 50mm F1.4 Classic weighs 216g, which means it is 159g (42%) lighter than the Pentax DA 55mm F1.4 SDM which has a weight of 375g.
Filter Threads
The Pentax FA 50mm F1.4 Classic has a filter size of 49mm whereas the Pentax DA 55mm F1.4 SDM has a 58mm diameter. Larger filters are generally more expensive than the smaller ones given all the other features are equal.
Below are links to the 49mm filters that we recommend you to consider for the Pentax FA 50mm F1.4 Classic:
And these are the 58mm filters that we recommend for the Pentax DA 55mm F1.4 SDM:
Lens Mounts
The Pentax FA 50mm F1.4 Classic has the Pentax KAF lens mount whereas the Pentax DA 55mm F1.4 SDM has the Pentax KAF3 lens mount. Some of the latest released cameras that are compatible with these mounts are Pentax K-3 III Mono, Pentax KF and Pentax K-3 III for the Pentax KAF Mount and , and for the Pentax KAF3 Mount.
Focal Range
Pentax FA 50mm F1.4 Classic 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 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.
