The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Pentax 50-200mm F4-5.6 ED and the Olympus ED 40-150mm f4-5.6 R for their suitability to various photography scenarios:
Size and Weight Comparison
The size of a lens is an important deciding factor when comparing two lenses. Olympus ED 40-150mm f4-5.6 R is the longer of the two lenses at 86mm. The Pentax 50-200mm F4-5.6 ED with a length of 80mm, is 6mm shorter. On the other hand, the Pentax 50-200mm F4-5.6 ED has a larger diameter of 69mm compared to the Olympus ED 40-150mm f4-5.6 R's 64mm diameter.
The weight of a lens is as important as its external dimensions, especially if you are planning to hand hold your camera and lens combination for longer periods. Olympus ED 40-150mm f4-5.6 R weighs 190g, 30% (82g) lighter than the Pentax 50-200mm F4-5.6 ED's weight of 272g.
Lens Mounts
The Pentax 50-200mm F4-5.6 ED has the Pentax KAF lens mount whereas the Olympus ED 40-150mm f4-5.6 R has the Micro Four Thirds lens mount. Some of the latest released cameras that are compatible with these mounts are Pentax KF, Pentax K-3 III and Pentax KP for the Pentax KAF Mount and OM System OM-5, Panasonic GH6 and OM System OM-1 for the Micro Four Thirds Mount.
Focal Range
Pentax 50-200mm F4-5.6 ED has a focal range of 50-200mm and 4.0X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of 75-300mm when used on a APS-C / DX format camera. Olympus ED 40-150mm f4-5.6 R has a focal range of 40-150mm and 3.8X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of 80-300mm when used on a FourThirds format camera.