objective mount for 77 mm filter mount

[GaryB]

I want to use my Nikon 80 - 200mm 2.8 with my microscope objectives but I haven't been able to locate a 77 mm filter ring to RMS objective adapter. Any ideas where I'd find such a beast or some other way to mount the objective?

[ChrisR]

52 is worth standardising on for Nikon so go 77 step down to 52 then a 52 to objective adapter.
The extra few mm length, won't matter.

[GaryB]

Thanks for that.