One of the downsides to shooting with smaller sensors shows up in Bokeh, or the quality and ability to render out of focus areas pleasingly. My favorite wide aperture lens of all time is the Canon 85mm f1.2 Version II for full format and the Panasonic/Leica Nocticron 42.5mm f1.2 for m43. Using the Nocticron on a micro 43 sensor gives a field of view equivalent of 85mm. So by shooting in the same spot, with about the same angle and framing, you can get an idea of the difference between a large format sensor, in this case, the Sony A7R3, and the Olympus OM-D E-m1 Mark2(god I hate Olympus naming conventions).
I deliberately choose a very dull subject matter to illustrate the dramatic difference. The Canon 85mmf1.2 can take something quite drab and generate interest, simply due to the narrow depth of field and quality of the out of focus areas. The Olympus, despite the illusion of equivalence in FOV, is just no match.
So even though the FOV is equivalent, the lenses are not as one is an 85mm lens, and the other behaves as a 42.5mm lens would on a full frame camera. Here the smaller sensor has cropped the image by a factor of two, so we get the depth of field of a lens with half the focal length.
Therefore, if you want to get the narrow depth of field that full frame offers, but on an m43 system, you will need to pick a comparable focal length AND aperture. Of course, you will also need to back up to twice the distance of full frame to keep the FOV the same.
The comparable lenses don’t exist, but the Olympus 75mmf1.8 will get you close, and it’s a beauty.
Image details – f1.2, Canon 85mm on top.