About that Bokeh (Another FF/m43 comparison)

Testing a new Oly 75mm wide open on E-PL5 from around 15 feet away (cropped).

I understand the technical objective of the OP and looking at the light bulb comparison, the D810 does have more blur but that wouldn't be my choice anyway. Being very personal, choices can be manipulated enough to make this a very trivial issue. More megapixels, more blur… it's all trivial now. I still have my Rollei TLR and it hardly gives me any more blur than my Oly 25mm f1.8 in a similar scenario. Reluctantly, I have to say that my E-PL5 can do even more on the street. It has more stealth than my O-MD or TLR but I don't mean to go off onto another debate, this is about DOF blur and I'd like to offer another consideration when choosing blur softness.

I prefer adding more information to the composition by relating background effects to the well pronounced subject, in order to build the story, having the background inject more information and elaborate on the subject. Again, it's a personal choice but I've seen a lot of nice detail shots weakened by too much background blur. I'd say the photo as an entirety matters more than anything, especially in the first few moments of seeing it on a wall, the initial impact or impression one may get before more detail evaluation. This is where 5 megapixels can outplay the advantages of 16 or more megapixels and I can be numb to numbers or formats.

Another consideration is that the OP test shot appears as a single background plane. I've always found more appeal with compounding amounts of blur, as a background recedes… usually more interesting. This alone may nullify any suggestion that one needs a larger format, or longer or faster lens to get softer blur effects. Focus and light falloff are great ingredients to master.

This shot, in NYC, has enough information in the background blur to indicate a city location, that she was probably sitting in relation to standing figures in the back. The circles in the blur accentuate the same in her eyes or what she's wearing. If I'd taken this same shot with extensive blur I'd have marred this opportunity. I may as well have shown you something that was taken in front of a bright mottled canvas backdrop in the studio… or wherever.