The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Pentax 70mm F2.4 AL L and the Canon 85mm f1.8 USM 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. Canon 85mm f1.8 USM is the longer of the two lenses at 72mm. The Pentax 70mm F2.4 AL L with a length of 26mm, is 46mm shorter. Besides being longer, the Canon 85mm f1.8 USM also has a larger diameter of 75mm 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 130g, which means it is 295g (69%) lighter than the Canon 85mm f1.8 USM which has a weight of 425g.
Filter Threads
The Pentax 70mm F2.4 AL L has a filter size of 49mm whereas the Canon 85mm f1.8 USM has a 58mm 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 Pentax 70mm F2.4 AL L:
And these are the 58mm filters that we recommend for the Canon 85mm f1.8 USM:
Lens Mounts
The Pentax 70mm F2.4 AL L has the Pentax KAF lens mount whereas the Canon 85mm f1.8 USM has the Canon EF 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 KAF Mount and Blackmagic URSA 12K LF, Z CAM E2-F6 II 6K and Z CAM E2-S6 II 6K for the Canon EF Mount.
Pentax 70mm F2.4 AL L is also available in the Pentax KAF mount.
Focal Range
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.
On the other hand, the Canon 85mm f1.8 USM is a prime lens with fixed focal lenght of 85mm. When it is mounted on an APS-C sensor camera with 1.6x crop, it provides a 35mm (FF) equivalent of 136mm.
