VariMag II Microscope Adapter for All Nikon DSLR Cameras

I've used Zeiss and Nikon compound and steromicroscopes for photomicrography for 40 years so I'm aware of many technical challenges that can arise with taking photographs through a microscope. Recently I used the VariMag II adapter with a Zeiss compound microscope and a Nikon D850 camera and no matter how hard I tried I was unable to produce images much better than with my iPhone and a $30 phone-to-microscope adapter! Very disappointing.I purchased this adapter directly on their website.