I enjoy portrait photography, especially with Nikon 85mm and 105mm lenses on full-frame cameras.
My gear is old and needs an upgrade. I'm considering M4/3 systems because of their size.
I read that M4/3 lenses don't generate a shallow DOF, something which is useful for portraits.
Why exactly is this and is it really a problem for portraits?
IMO - FF or medium format with super fast portrait length lenses are over rated. And I do own the Sigma 105mm F1.4. There is a point where the DOF is too shallow for normal photography and best reserved for effects photography.
DoF is only then too shallow when you dont know what youre doing. Full body portraits (of a couple) from larger distance with 75mm aperture opening like 105mm f1.4 or 135mm f1.8 are absolutely
stunning , and the DoF is a key criteria to make them isolated from background. Only in theory this is possible with m43.
I think the point here isn't that FF can isolate more than MFT. This is obvious and not the thing that people are arguing with.
The question is how tiny do you want your DoF to be, and most of the time to shallow of a DoF is a very lazy way to compose your shot.
Sure, it looks nice, but you lose all context to the shot. You just have a sharp thing in the middle of a blurry background. It looks cool because this is not what we're used to see, but I agree with tammons here, this is really overrated. It has been used and used and used to saturation and besides a few examples where DoF is used creatively, this is not really the kind of images I like to see or even make myself. I like some subject separation, but too much of it simply makes the photo appear lazy in my opinion.
One of my favorite MFT Bokeh lenses is the Oly 12-100mm F4. Not a portrait lens but I got some great Bokeh effect shots with a very nice focus falloff.
largerst aperture opening on this 200mmf8 equivalent is 25mm, which is the same as a FF 35mmf1.4. Sure its enough, but with 200mm you will be very very limited in the photos you can take compared to 35mm, where with hi-mp you can absolutely crop in post to 100mmf4 equivalent (8MP left). 35mmf1.4-100mmf4 for a similar price than 12-100f4. theres just no contest...
Who even said that we even wanted to have 35mm f/1.4 depth of field? I use my 40mm f/2 on my Nikon Z6 a lot, and I'm stopping down constantly because even that lens kind of obliterates the background the moment you get close enough to your subject (not mentioning the DoF simply becomes too shallow).
Same thing with longer lenses like my 85mm f/1.8. I generally don't get wider than f/2.8 when I really want to destroy the background, generally I'm more shooting around f/3.5 or f/4.
me away 
