The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Sigma 85mm F1.4 EX DG HSM and the Pentax DA 50-135mm F2.8 ED 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 DA 50-135mm F2.8 ED is the longer of the two lenses at 136mm. The Sigma 85mm F1.4 EX DG HSM with a length of 88mm, is 48mm shorter. On the other hand, the Sigma 85mm F1.4 EX DG HSM has a larger diameter of 86mm compared to the Pentax DA 50-135mm F2.8 ED's 77mm 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 DA 50-135mm F2.8 ED weighs 685g, 5% (40g) lighter than the Sigma 85mm F1.4 EX DG HSM's weight of 725g.
Filter Threads
The Sigma 85mm F1.4 EX DG HSM has a filter size of 77mm whereas the Pentax DA 50-135mm F2.8 ED 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 77mm filters that we recommend you to consider for the Sigma 85mm F1.4 EX DG HSM:
And these are the 67mm filters that we recommend for the Pentax DA 50-135mm F2.8 ED:
Lens Mounts
The Sigma 85mm F1.4 EX DG HSM has the Pentax KAF3 lens mount whereas the Pentax DA 50-135mm F2.8 ED has the Pentax KAF2 lens mount. Some of the latest released cameras that are compatible with these mounts are Pentax K-3 III Mono, Pentax KF and Pentax K-3 III for the Pentax KAF3 Mount and , and for the Pentax KAF2 Mount.
Sigma 85mm F1.4 EX DG HSM is also available in the Canon EF , Nikon F (FX), Sony Alpha and Sigma SA mounts.
Focal Range
Sigma 85mm F1.4 EX DG HSM 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 DA 50-135mm F2.8 ED has a focal range of 50-135mm and 2.7X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of 75-202.5mm when used on a APS-C / DX format camera.
