The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Sony 85mm F2.8 SAM and the Pentax 70mm F2.4 AL L 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 85mm F2.8 SAM is the longer of the two lenses at 52mm. The Pentax 70mm F2.4 AL L with a length of 26mm, is 26mm shorter. Besides being longer, the Sony 85mm F2.8 SAM also has a larger diameter of 70mm compared to the Pentax 70mm F2.4 AL L's 63mm 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 70mm F2.4 AL L weighs 147g, 16% (28g) lighter than the Sony 85mm F2.8 SAM's weight of 175g.
Filter Threads
The Sony 85mm F2.8 SAM has a filter size of 55mm whereas the Pentax 70mm F2.4 AL L has a 49mm diameter. Larger filters are generally more expensive than the smaller ones given all the other features are equal.
Below are links to the 55mm filters that we recommend you to consider for the Sony 85mm F2.8 SAM:
And these are the 49mm filters that we recommend for the Pentax 70mm F2.4 AL L:
Lens Mounts
The Sony 85mm F2.8 SAM has the Sony Alpha lens mount whereas the Pentax 70mm F2.4 AL L has the Pentax KAF lens mount. Some of the latest released cameras that are compatible with these mounts are Sony A99 II, Sony A68 and Sony A77 II for the Sony Alpha Mount and Pentax K-3 III Mono, Pentax KF and Pentax K-3 III for the Pentax KAF Mount.
Pentax 70mm F2.4 AL L is also available in Pentax KAF mount.
Focal Range
Sony 85mm F2.8 SAM 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 70mm F2.4 AL L is a prime lens with fixed focal lenght of 70mm which has an effective (full-frame 35mm equivalent) focal range of 105mm when used on a APS-C / DX format camera.
