I'm not a Nikon user so I'm not much interested in those Cosina/Zeiss ZF lenses, but I loved Zeiss glass for Y/C SLR and Hassy.
But, If I were, I would wait for a while, maybe several years and see what user say about them. Then buy if liked.
Because, they are Zeiss branded and should be optically good, but still are Cosina's anyway. I do not know how you(users outside Japan) think/feel about Cosina products, but I've seen for years and still see many craps from them.
I can see and touch them at many shops here in Tokyo. They have cameras and lenses for in-store trial. Most of, you may not believe me but, most of them are broken. Cheap Voightlandar brands are of course, expensive Zeiss brand lenses are also. I know they are roughly handled and tend to have short life. But, I have never seen Canon, Nikon or other respected products which are also served as trial use fail that much often like Cosina's.
I see many ZM lenses, such as ZM50/1.5, ZM35/2.0, in used camera shops lately. They are not old, they were launched not far from now of course, but I often see them labeled as "with problem" or something mostly on helicoids. I have once told my friends that and they agreed. I don't check ZF lenses(I'm not a Nikonian) so I don't know about them, but could guess the same.
Many says Cosina products have become good, they can be highly ranked. I DO NOT believe that.
Even in Japan, young users who don't know cosina before Cosina/Voigtlandar say they are nice, but many, especially my age and older still rate cosina as what cosina used to be.
Cosina/Voigtladar lenses are fine, because they are inexpensive. I think they are as good as for its price. But I don't understand why one need to pay that much money for Cosina/Zeiss.
I would like to belive that Cosina/Zeiss are as good as Nikon/Canon or such, but still can not.
I believe that Cosina/Zeiss are optically good. They have Zeiss performance and tested in the Zeiss way. I see many test reports tell they are good.
But how about endurance ? How robust are they ? Can they be compared with Nikons only by optics ? Who can tell how they are good only with bench marks and quick field tests ?
Several years after now, how many of them are working fine ? I DO NOT know.
Nikon products have been proven for years and years. That's will be why I buy Nikon(If I were Nikonian). I myself is a Canon MF user. I've been using Canon camera and lenses from 20-30 years ago. They are working just fine.
Is there anyone using 30 years old Cosina camera or lense ?