I tried this at my D500 first but ERR messages appeared although the camera didnt stop shooting, still not enough mirror clearance?
later i added another ring as spacer and tried it on the Df with the aperture lug turned in, no error messages on the Df.
Just arrived in France from England...
Fons, that combination I showed previously worked fine with the D700 as well.
BTW, I noticed on the picture of your 55mm CRT that the threaded rear doesn't protrude like mine. Seems few mm shorter ?
I didn't bring it with me to France, so can't measure it for comparison.
The second flower with the V1 is nice ! I like the detail of stamens.
it reminds me a borage flower.