ZWO Nikon Lens Adapter
I haven't had it long, but it seems to do the job. It is well made -- solid metal with good internal light baffles. As a simple adapter, as expected it didn't come with any instructions. That said, it came with three "shims" that are most likely intended for fine-tuning the lens to sensor spacing. A note to that effect (and just where place them -- there are two places you can use them) would have been useful. But I'm quite satisfied since this adapter allows me to use my fairly wide range of Nikon lenses either for imaging or as guide scopes.
Works as advertised
Borrowed one from a friend for monochrome luminance imaging using a 6.5 mm back-focus ASI 1600 Pro Cooled camera and a 2” threaded IR cut filter, with a vintage Nikon 4.0 ED 300 mm AIS lens. Used the 11 mm spacer ring to achieve 46.5 mm back-focus for the Nikon lens! For aperture control I use the trick of placing a stack of step down rings in the thread on the front of the lens. Now that I’ve ordered a new ASI 2600 MM with 17.5 mm back-focus I’d really like to use a 36 mm ZWO 7 position filter wheel. Unfortunately there is now way to achieve the 46.5mm back focus with the 20 mm additional path front wheel filter wheel. Wish ZWO would make a version of the adapter with 9 mm thickness. I’m certain I’m not alone wanting that capability!
No aperture control
This product should include a mechanism to open the aperture. I have an older adapter, completely useless for the ZWO products, but it does have a convenient lever to control aperture.