The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Sony FE 24-105mm F4 G OSS and the Pentax 17-70mm F4.0 AL SDM 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. Sony FE 24-105mm F4 G OSS is the longer of the two lenses at 113mm. The Pentax 17-70mm F4.0 AL SDM with a length of 94mm, is 19mm shorter. Besides being longer, the Sony FE 24-105mm F4 G OSS also has a larger diameter of 83mm compared to the Pentax 17-70mm F4.0 AL SDM's 75mm 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 17-70mm F4.0 AL SDM weighs 485g, 26% (178g) lighter than the Sony FE 24-105mm F4 G OSS's weight of 663g.
Filter Threads
The Sony FE 24-105mm F4 G OSS has a filter size of 77mm whereas the Pentax 17-70mm F4.0 AL SDM 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 Sony FE 24-105mm F4 G OSS:
And these are the 67mm filters that we recommend for the Pentax 17-70mm F4.0 AL SDM:
Lens Mounts
The Sony FE 24-105mm F4 G OSS has the Sony E lens mount whereas the Pentax 17-70mm F4.0 AL SDM has the Pentax KAF3 lens mount. Some of the latest released cameras that are compatible with these mounts are Sony FX5, Sony A7R VI and Sony A7 V for the Sony E Mount and , and for the Pentax KAF3 Mount.
Focal Range
Sony FE 24-105mm F4 G OSS has a focal range of 24-105mm and
4.4X zoom ratio . When it is mounted on an APS-C sensor camera with 1.5x crop, it provides a 35mm (FF) equivalent of
36 - 157.5mm.
On the other hand, the Pentax 17-70mm F4.0 AL SDM has a focal range of 17-70mm and 4.1X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of 25.5-105mm when used on a APS-C / DX format camera.
