Birna coach me in that very same thing. We used a little bit of toothpick to hold the lever for the aperture.
Z9, 10.5mm in fx mode
In this thread:... https://nikongear.net/revival/index.php?topic=11155.45https://nikongear.net/revival/index.php?topic=11155.45https://nikongear.net/revival/index.php?topic=11155.45
Nice to be reminded about that creative thread. I must say I am a little nervous about jamming tooth picks and other objects inside the cavity shared with the shutter shield and sensor, although I have done the same in the past for testing purposes using a tiny longitudinal cut piece of Tygon tubing. Also taping the contacts is also a bit cumbersome. So I did a little search and found the following post with a simple solution:
https://www.dpreview.com/forums/post/63688978:
1. Simply mount the 10.5mm and FTZ adapter normally without any modification.
2. Set aperture as intended. If set aperture is narrower than 5.6 activate and keep pressing the button that has been configured for depth of field preview.
3. Then immediately press lens release button on the body and twist the FTZ adapter just a smidge until F-- shows at the top display. The body will now be in FX mode with the lens remaining at the last activated aperture and body will see the lens as fully manual.
(It would now be possible to tape the contacts on the body side of the FTZ adapter if one wanted to be able to mount it locked in place with last set aperture remaining.)
This is the same trick I use with my 500PF when using it with my astrocamera. The FTZ adapter acts similar to an E-lens (or Z lens) when disconnecting without powering down the body. This is against Nikon's instructions for dismounting procedure but with DSLRs I always forgot to turn body off before dismounting lens. (With Z8/Z9 it of course is best to normally follow instructions so that the shield is activated.)
