Girlfriend asked me if there is a macro lens for Nikon 1 J2. So far I only found Besel Macro2. This does look more like extension tube then lens. Does anyone has experience with this product or is anyone aware of any macro lens for Nikon 1 J2?
There isn't one as such, at least not in the sense of a lens having a 1:1 reproduction ratio at the sensor.
The closest in Nikon's stable of CX lenses would be the standard 10-30mm kit zoom at the longest focal length (30mm) and closest focusing distance (20cm/8"). Yes, that does only yield a 1:4.8 magnification ratio on the sensor, but that's where the normal definition of macro starts to get a little wonky with small-sensor cameras. That 1:4.8 reproduction ratio on the CX sensor is equivalent to 1:1.77 on a full-frame sensor. So, while the lens itself may not qualify as a "macro lens" according to some definitions, the pictures the system produces when viewed at normal resolutions would, by most standards, qualify as "macro shots". (Keeping in mind, of course, that the term macro has traditionally covered photography in the 1:4 to 4:1 range, and that it's not uncommon to see lenses, especially zooms, with a maximum reproduction ratio of 1:2 or 1:4 labelled as "macro". A 1:1 reproduction ratio on a 1/2.3"-type sensor, for instance, would take one into the realm of microphotography under ordinary viewing conditions.)
For more specialized, higher-magnification photography, Nikon does offer a solution with the FT-1 mount adapter. Any one of the Micro Nikkor lenses can then be used with the Nikon 1 system, and all will provide a 1:1 maximum actual or 2.7:1 maximum equivalent reproduction ratio (and all of them will have a considerable stand-off distance for 1:1-equivalent photography). And, as you've noted, you can use extension tubes when losing infinity focus temporarily isn't going to be a problem.