Got my Viltrox NF-M1 - impressed!
Jan 23, 2021
3
I discovered this item just recently and was anxious to try it out on my E-M5 II. I have a number of Nikon lenses, but was particularly interested in using the AF-S 300 f/4 (older D model, not the newer Phrase Fresnel VR design).
After playing around with it a bit, I'm impressed at how well it all works. Connections are reasonably solid, and since I'm using the tripod foot on the lens, I don't have to worry about the NF-M1 getting in the way of my camera L bracket (which I have confirmed it does).

Autofocus is quite fast and about as accurate as I could expect with a Nikon body, although manual focus seems to be more accurate. Depth of field at a few feet and f/4 is miniscule. The E-M5 even recognizes when I'm overriding AF by turning the focus ring on the lens, just like with my Olympus lenses, although it doesn't stay zoomed in long enough to get really precise focus. What worked better was zooming the display manually and focusing that way, with the camera set to MF. Turning the switch on the Viltrox to MF also disables camera aperture control, so seems a bit pointless.
After some experimentation, I found that delayed silent mode produced the sharpest images at low shutter speeds (like 1/10). Neither anti-shock mode nor the camera's IBIS eliminated enough shake to get really sharp images. (This Nikon lens has no built-in stabilization.)
Here's one of my test setups and a few images:

Shrek:

100% crop at f/4 (default Lightroom settings):

100% crop at f/5.6:

I've used this lens previously in a Nikon 1 setup (2.6x crop), so I figured the results on m43 would be acceptable.
100% crop of 12-40 pro lens at f/5.6:

100% crop of chandelier light bulb filament at f/4:

Haven't tried using my 1.4 TC yet, but that will be next.
It may not be as good as the Olympus 300mm, but not bad for spending less than $200!