Putting aside all the possible comparisons between price, camera systems, sensor size and focal lengths (real and equivalent), I think it is also fair to remind ourselves that right now, there is nothing like the 300mm f/4 in the M4/3 system. The Image Stabilization (IS) works differently depending on the combination of OLYMPUS Micro Four Thirds cameras and the M.ZUIKO DIGITAL ED 300mm F4.0 IS PRO lens. The following describes how the Image stabilization (IS) works:

Additionally, when this lens is paired with the newer Olympus bodies like the OM-1, the lens and camera work superbly together with excellent image stabilization and autofocus. The stabilization is most effective when paired with Olympus bodies, where synchronized image stabilization will give you up to 6 stops stabilization. Wildlife photography simply became much easier with a modern lens/camera combo like this. Close Focusing AbilityThe M.Zuiko 300mm f/4 is the fifth professional lens produced by Olympus for Micro Four Thirds. Its development was first announced in 2014 at Photokina but the release was delayed to add optical stabilisation – a wise move as it makes this telephoto lens an interesting choice for Panasonic customers as well. If you turn off the image stabilization in the lens, the image stabilization in the camera turns off simultaneously. As a macro and herp photographer, I am also impressed by the 1.4m minimum focusing distance on the Olympus 300mm f/4. At such a close range, this allows for an image reproduction ratio of 1:4, which is much greater than you’ll usually find on a long telephoto lens. Combined with the maximum aperture, this can create a very nice bokeh and a ‘telephoto look’ for portraits of smaller animals. And the 2x crop factor of Micro Four Thirds means you can fill the frame with very small subjects. DC-G9 + OLYMPUS M.300mm f/4 @ 300mm, ISO 125, 1/200, f/4.0 Competition

Bokeh is a word used for the out-of-focus areas of a photograph, and is usually described in qualitative terms, such as smooth / creamy / harsh etc. In the Olympus M.ZUIKO Digital ED 300mm f/4 IS Pro, Olympus employed a nine circular-bladed diaphragm, which produces some very nice bokeh, at least in our opinion. However, recognising that bokeh evaluation is subjective, we have provided a few examples for your perusal. This needs to stop. I've read your article and how you resized images and compared noise levels concluding that a physically smaller sensor has more noise. This leads me to conclude that you are more familliar with old film than state of the art digital sensors.The Olympus M.ZUIKO Digital ED 12-40mm f/3.5-6.3 EZ lens is compatible with the MC-14 1.4x Teleconverter to provide a 420mm focal length, equivalent to 840mm in the 35mm format. By comparison, it is 6.7cm longer, 1.3cm larger and 510g heavier than the M.Zuiko 40-150mm f/2.8 Pro ( see our review here) that was previously the largest M4/3 lens on the market.

Chromatic aberrations, typically seen as purple or green fringes along contrasty edges, are only really noticeable by their almost complete absence from our test images. The Olympus M.ZUIKO Digital ED 12-40mm f/3.5-6.3 EZ lens features a 77mm filter thread which does not rotate on focus, great news for anyone intending to use a polariser or ND grads on the lens. The image stabilization in the camera and the lens can be used separately. To turn off image stabilization completely, make sure to turn off image stabilization in both the lens and the camera body.The Olympus 300mm f/4.0 IS PRO is a prime lens fixed at 300mm. There are longer options available for Micro Four Thirds that reach up to 400mm. However, the Olympus 300mm f/4.0 IS PRO is so sharp and high performing it feels like it is over 300mm, simply because the increased sharpness allows more cropping compared to the Olympus 100-300mm f/4-5.6 that I previously used. In taking pictures of surfers while I was sitting on a log, I found that the 100-400 at 400 was sharper than the 300 with the 1.4x teleconverter, assuming both were wide open. Some people commented on my post that the 300 with the teleconverter needs to be stopped down by one stop. I didn’t test that and the 300 is probably indistinguishable from the 100-400 in that case.