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 Samyang 85mm F1.4 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. Samyang 85mm F1.4 is the longer of the two lenses at 75mm. The HD Pentax-FA 77mm F1.8 Ltd with a length of 48mm, is 27mm shorter. Besides being longer, the Samyang 85mm F1.4 also has a larger diameter of 78mm compared to the HD Pentax-FA 77mm F1.8 Ltd'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. HD Pentax-FA 77mm F1.8 Ltd weighs 270g, which means it is 269g (49%) lighter than the Samyang 85mm F1.4 which has a weight of 539g.
Below you can find the dimension and weight table of the Telephoto Prime Lenses in Pentax KAF Mount for size comparison purposes.
Telephoto Lenses in Pentax KAF Mount for Size Comparison
Filter Threads
The HD Pentax-FA 77mm F1.8 Ltd has a filter size of 49mm whereas the Samyang 85mm F1.4 has a 72mm 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 72mm filters that we recommend for the Samyang 85mm F1.4:
Lens Mounts
Both the HD Pentax-FA 77mm F1.8 Ltd and the Samyang 85mm F1.4 has the same Pentax KAF lens mount. Some of the latest released cameras that are compatible with the Pentax KAF lenses are Pentax K-3 III Monochrome, Pentax KF and Pentax K-3 III.
Samyang 85mm F1.4 is also available in Canon EF , Nikon F (FX), Four Thirds, Sony Alpha, Sony E and Samsung NX mounts.
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 Samyang 85mm F1.4 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.