I have been using fountain pens for a while now. This is a Majohn P139, nib size #8 just replaced with an "F" that suits better my needs.

  Z50II @3200 iso -not too shabby- , 55mm 3.5 pre-ai

A nice Photo and a fantastic pen. I loved it, but lost it.

A bit late to the party, but as the original author of the modification, I thought I'd comment:
I originally made this modification exclusively to use on my f/8.0 reflex lens. So don't get talked out of trying it on yours - it works beautifully in daylight, just don't expect autofocus to work well as it gets darker ;-)

PDAF autofocus depends on light coming in from distinguishable different directions to the sensor.  The normal specs are for a circular aperture and a lens that uniformly does not vignette significantly.  I am not sure how the f/8.0 spec works, but I suspect it is more about light admission than outer aperture diameter.  That means that a reflex lens (with its donut-shaped aperture) will deliver light from wider angles than the spec would suggest.  Vignetting due to lens mount diameter issues would make PDAF stop working too far from the center of the image (but often there aren't any AF points there anyway) but again work with larger inclination than one would suspect from the aperture number.

In a nutshell: worth trying out, even if Nikon refuses to guarantee anything working.

CANDILEJA. Arisarum vulgare

Erwin Olaf - Freedom

https://www.stedelijk.nl/en/exhibitions/erwin-olaf-en

https://www.e-infin.com/eu/de/item/12901/spiegellose_digitalkamera_nikon_z8_(nur_geh%C3%A4use)

Interesting Frank
You told me about e-infin a while back after Jan Anne had recommended them.
I bought a D500 and a kit zoom lens at prices much below that of new items

I knew they were likely to be reconditioned but assumed warranty would deal with any issues
However my results moving from an equivalent d300 & comparable zoom weren't as good.

I think the zoom had issues but I was never able to get to the bottom of it. There was no Nikon warranty - just return to the vendor.