To improve on the images (separation of subject and background and blurring of background) a much larger f stop would be required.
To get the SAME depth of field standing on the same spot you need a longer focal length (2.7 times longer) and you have to stop down 2.7 times.
Those images were taken with the following lens settings:
Image 1: 110mm f/5.6
Image 2: 83.2mm f/5
Image 3: 83.2mm f/5
Image 4: 61.6mm f/4.5
Image 5: 49.3mm f/4
To take identical images from the same spot with my D800 I need the 70-300GVR, which is a real budget lens, and would need to set the lens according to:
Image 1: 297mm f/15
Image 2: 224.6mm f/13.5
Image 3: 224.6mm f/13.5
Image 4: 166.3mm f/12
Image 5: 133.1mm f/11
The above will give you EXACTLY the same separation, background blur or DOF, call it whatever you like. The bokeh will of course be different, since bokeh is based the lens and depends on the quality of the lens, but the 70-300GVR has very similar bokeh compared to teh 30-110, in fact a little better in my opinion, based on my taste.
Now, of course, "
to improve on the images" as you say it, i.e. to decrease the DOF, you must increase the aperture, but that is no issue at all, considering the above listed aperture settings for the D800/70-300 combo. It is obvious that the margins are quite huge, I can decrease the DOF by 2.7 without ANY serious effort, other than opening up the aperture of that cheap 70-300.
If you want to use the same lens with the same focal length, for example the 85/1.8, which is another cheap lens, things change a bit. Take the second image as example, it is taken with 83mm setting and that is pretty close to 85mm, so using the FT-1, an identical image could have been taken with the 85 set to f/5 from the same spot. Now, still using the exact same lens on the D800, to frame it equally we of course need to move closer, so let's assume that image 2 is taken from 5 meters distance originally, which means that with the D800 we need to be 1.85 meters from the subject. I hope we agree on this.
Lets move to DOF data, with the assumption that the subject distance is 5 meters in image 2, lens is now 85mm and the aperture is f/5, as in the original. This results in a total DOF of 0.38 meters. When using the D800 with the same lens I must move to 1.85 meters from the subject, but if I keep the same aperture I get 0.14 meter DOF which is considerably less than the 0,38 meters I had using the V1, and again, to get the same separation I must still stop down to f/13.5.
In short, saying that with a DSLR you need f/1.4 lenses is TOTALLY wrong. No matter what we do, the Nikon 1 is NOT the right system for narrow DOF, it is always easier to get narrow DOF with a DSLR, the larger the sensor the easier it is.