The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Pentax-D FA 85mm F1.4 ED SDM AW and the Pentax D FA 645 55mm F2.8 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 85mm F1.4 ED SDM AW is the longer of the two lenses at 124mm. The Pentax D FA 645 55mm F2.8 with a length of 68mm, is 56mm shorter. Besides being longer, the Pentax-D FA 85mm F1.4 ED SDM AW also has a larger diameter of 95mm compared to the Pentax D FA 645 55mm F2.8's 81mm 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 645 55mm F2.8 weighs 416g, 66% (839g) lighter than the Pentax-D FA 85mm F1.4 ED SDM AW's weight of 1255g.
Filter Threads
The Pentax-D FA 85mm F1.4 ED SDM AW has a filter size of 82mm whereas the Pentax D FA 645 55mm F2.8 has a 67mm diameter. Larger filters are generally more expensive than the smaller ones given all the other features are equal.
Below are links to the 82mm filters that we recommend you to consider for the Pentax-D FA 85mm F1.4 ED SDM AW:
And these are the 67mm filters that we recommend for the Pentax D FA 645 55mm F2.8:
Lens Mounts
The Pentax-D FA 85mm F1.4 ED SDM AW has the Pentax KAF4 lens mount whereas the Pentax D FA 645 55mm F2.8 has the Pentax 645AF2 lens mount. Some of the latest released cameras that are compatible with these mounts are , and for the Pentax KAF4 Mount and Pentax 645Z, Pentax 645D and for the Pentax 645AF2 Mount.
Focal Range
Pentax-D FA 85mm F1.4 ED SDM AW is a prime lens with fixed focal lenght of 85mm. When it is mounted on an APS-C sensor camera with 1.5x crop, it provides a 35mm (FF) equivalent of
127.5mm.
On the other hand, the Pentax D FA 645 55mm F2.8 is a prime lens with fixed focal lenght of 55mm.
