The type of photography that you are planning to use is an important decision factor. Here we have evaluated the HD Pentax-FA 31mm F1.8 Ltd and the Lensbaby Burnside 35 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. Lensbaby Burnside 35 is the longer of the two lenses at 70mm. The HD Pentax-FA 31mm F1.8 Ltd with a length of 69mm, is 1mm shorter. Besides being longer, the Lensbaby Burnside 35 also has a larger diameter of 70mm compared to the HD Pentax-FA 31mm F1.8 Ltd'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. HD Pentax-FA 31mm F1.8 Ltd weighs 341g, which means it is 33g (8%) lighter than the Lensbaby Burnside 35 which has a weight of 374g.
Filter Threads
The HD Pentax-FA 31mm F1.8 Ltd has a filter size of 58mm whereas the Lensbaby Burnside 35 has a 62mm diameter. Larger filters are generally more expensive than the smaller ones given all the other features are equal.
Below are links to the 58mm filters that we recommend you to consider for the HD Pentax-FA 31mm F1.8 Ltd:
And these are the 62mm filters that we recommend for the Lensbaby Burnside 35:
Lens Mounts
Both the HD Pentax-FA 31mm F1.8 Ltd and the Lensbaby Burnside 35 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.
Lensbaby Burnside 35 is also available in Canon EF , Fujifilm X, Micro Four Thirds, Nikon F (FX), Samsung NX, Sony Alpha and Sony E mounts.
Focal Range
HD Pentax-FA 31mm F1.8 Ltd is a prime lens with fixed focal lenght of 31mm. When it is mounted on an APS-C sensor camera with 1.5x crop, it provides a 35mm (FF) equivalent of
46.5mm.
On the other hand, the Lensbaby Burnside 35 is a prime lens with fixed focal lenght of 35mm. When it is mounted on an APS-C sensor camera with 1.5x crop, it provides a 35mm (FF) equivalent of 52.5mm.