The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Canon RF 70-200mm F2.8L IS USM 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. Canon RF 70-200mm F2.8L IS USM is the longer of the two lenses at 146mm. The Pentax DA 50-135mm F2.8 ED with a length of 136mm, is 10mm shorter. Besides being longer, the Canon RF 70-200mm F2.8L IS USM also has a larger diameter of 90mm 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, 35% (385g) lighter than the Canon RF 70-200mm F2.8L IS USM's weight of 1070g.
Filter Threads
The Canon RF 70-200mm F2.8L IS USM 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 Canon RF 70-200mm F2.8L IS USM:
And these are the 67mm filters that we recommend for the Pentax DA 50-135mm F2.8 ED:
Lens Mounts
The Canon RF 70-200mm F2.8L IS USM has the Canon RF 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 Canon R6 V, Canon R6 III and Canon C50 for the Canon RF Mount and , and for the Pentax KAF2 Mount.
Focal Range
Canon RF 70-200mm F2.8L IS USM has a focal range of 70-200mm and
2.9X zoom ratio . When it is mounted on an APS-C sensor camera with 1.6x crop, it provides a 35mm (FF) equivalent of
112 - 320mm.
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.
