Size and Weight Comparison
Size of a lens is an important deciding factor when comparing two lenses.Olympus ED 40-150mm F2.8 Pro is the longer of the two lenses at 160mm. The Panasonic 45-150mm F4-5.6 OIS with a length of 73mm is 87mm shorter. Besides being longer, the Olympus ED 40-150mm F2.8 Pro also has a larger diameter of 79mm compared to Panasonic 45-150mm F4-5.6 OIS's 62mm diameter.
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. Panasonic 45-150mm F4-5.6 OIS weighs 200g, 280% (560g) lighter than the Olympus ED 40-150mm F2.8 Pro's weight of 760g.
Below you can find the dimension and weight table of the 'Telephoto Zoom Lenses in Micro Four Thirds Mount for size comparison purposes.
Telephoto Zoom Lenses in Micro Four Thirds Mount for Size Comparison
Lens Mounts
Both Olympus ED 40-150mm F2.8 Pro and Panasonic 45-150mm F4-5.6 OIS has the same Micro Four Thirds lens mount. Some of the latest released cameras that are compatible with the Micro Four Thirds lenses are Panasonic GH6, OM System OM-1 and Panasonic GH5 II.
Focal Range
Olympus ED 40-150mm F2.8 Pro has a focal range of 40-150mm and 3.8X zoom ratio which has a 35mm equivalent focal range of 80-300mm when used on a FourThirds format camera. Panasonic 45-150mm F4-5.6 OIS has a focal range of 45-150mm and 3.3X zoom ratio which has a 35mm equivalent focal range of 90-300mm when used on a FourThirds format camera.