The type of photography that you are planning to use is an important decision factor. Here we have evaluated the HD Pentax-FA 77mm F1.8 Ltd and the Pentax-D FA 85mm F1.4 ED SDM AW 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 HD Pentax-FA 77mm F1.8 Ltd with a length of 48mm, is 76mm shorter. Besides being longer, the Pentax-D FA 85mm F1.4 ED SDM AW also has a larger diameter of 95mm compared to the HD Pentax-FA 77mm F1.8 Ltd's 64mm diameter.
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Below you can find a scaled side-by-side image of HD Pentax-FA 77mm F1.8 Ltd and Pentax-D FA 85mm F1.4 ED SDM AW to get a better idea of how their sizes compare in real life.
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. HD Pentax-FA 77mm F1.8 Ltd weighs 270g, which means it is 985g (78%) lighter than the Pentax-D FA 85mm F1.4 ED SDM AW which has a weight of 1255g.
Filter Threads
The HD Pentax-FA 77mm F1.8 Ltd has a filter size of 49mm whereas the Pentax-D FA 85mm F1.4 ED SDM AW has a 82mm 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 HD Pentax-FA 77mm F1.8 Ltd:
And these are the 82mm filters that we recommend for the Pentax-D FA 85mm F1.4 ED SDM AW:
Lens Mounts
The HD Pentax-FA 77mm F1.8 Ltd has the Pentax KAF lens mount whereas the Pentax-D FA 85mm F1.4 ED SDM AW has the Pentax KAF4 lens mount. Some of the latest released cameras that are compatible with these mounts are Pentax K-3 III Monochrome, Pentax KF and Pentax K-3 III for the Pentax KAF Mount and , and for the Pentax KAF4 Mount.
Focal Range
HD Pentax-FA 77mm F1.8 Ltd 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.
On the other hand, the 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.