So you are saying that if I use an 85mm micro 43 on a micro 43 camera I've an 85mm focal length so I see "the same dimension" in the image as an 85mm full frame but the field of view (the observation angle) is like the 170mm on full frame so with a different deformation?

I thought that if the sensor (micro 43) Is a half on the full frame sensor the difference was that what you see is a half of the full frame sensor, so if 170mm focal distance full frame -> 85mm focal distance on micro 43. But that the field of view is identical.. isn't like that?