With 5mm extension helicoid some RF lensえs can focus much closer. Everything is snuggly fit,
movement is smooth, infinity is no problem. It is made by Hawks Factory in Taiwan, is worth
its high price for me. Of course the most of lenses aren't designed to perform well, since
rangefinder lenses do no focus to less than 0.7m which is PITA. BTW, this is a perfect match
for the both Nikkor-O 55/1.2 and Ultra-Micro-Nikkor 55/2 since you can focus from infinity to
~0.5m for NEX cameras without any other ring/tubes except L->M mount adapter. Although
these Nikkors are not designed for a general shooting, they work fine when closed down.