Eric Sande , Apr 26, 2010; 12:59 p.m.
I used this combo for awhile on a D2x. Since the cup sits away from the viewfinder, the ring can easily come off. The cup came off mine on the first outing. I did find it, but the ring was never seen again. I think if I were to attempt that setup again I'd put some drops of super glue around the ring and make it permanent.
DK-17M with DK-19 eye cup