The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Sony FE 40mm F2.5 G and the Pentax FA 77mm 1.8 L 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 FA 77mm 1.8 L is the longer of the two lenses at 48mm. The Sony FE 40mm F2.5 G with a length of 45mm, is 3mm shorter. On the other hand, the Sony FE 40mm F2.5 G has a larger diameter of 68mm compared to the Pentax FA 77mm 1.8 L's 64mm 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. Sony FE 40mm F2.5 G weighs 173g, which means it is 97g (35%) lighter than the Pentax FA 77mm 1.8 L which has a weight of 270g.
Filter Threads
Both the Sony FE 40mm F2.5 G and the Pentax FA 77mm 1.8 L have the same Filter thread size of 49mm.
Below are links to the 49mm filters that we recommend you to consider for these lenses:
Lens Mounts
The Sony FE 40mm F2.5 G has the Sony E lens mount whereas the Pentax FA 77mm 1.8 L has the Pentax KAF lens mount. Some of the latest released cameras that are compatible with these mounts are Sony FX5, Sony A7R VI and Sony A7 V for the Sony E Mount and Pentax K-3 III Mono, Pentax KF and Pentax K-3 III for the Pentax KAF Mount.
Focal Range
Sony FE 40mm F2.5 G is a prime lens with fixed focal lenght of 40mm. When it is mounted on an APS-C sensor camera with 1.5x crop, it provides a 35mm (FF) equivalent of
60mm.
On the other hand, the Pentax FA 77mm 1.8 L is a prime lens with fixed focal lenght of 77mm. When it is mounted on an APS-C sensor camera with 1.5x crop, it provides a 35mm (FF) equivalent of 115.5mm.
