I would like to leave my lens fully open all the time without having to find an aperture converter. But other than bluetac I cannot find anything that would attach to my Nikon lens and leave it continually open.

I have a Chronos 2.1-HD High Speed Camera with MFT mount, and I will only ever need to use this lens fully open.

I plan to buy a focal reducer, but looking for a Nikon to MFT mount, none have aperture controls on them. As I will always been needing the F-stop in its lowest position, I thought/hoped there might be a situation where I could find a way to leave the F-stop "open".

Nikon lens mount

  • \$\begingroup\$ How is the camera controlling the aperture in the first place? It appears to be a CS/C thread mount camera with no electronic or mechanical couplings to the lens, so if you use a Nikon F to C mount adapter, the aperture should be what you manually set on either the aperture ring on the lens, or in case of a "G" lens, the aperture ring on the adapter (if the adapter has one). A Nikon "AF-P" lens will probably not be usable on this camera. Maybe it will help if you make clear what exact Nikon lens model you are using. \$\endgroup\$ Commented Feb 21, 2022 at 20:33

1 Answer 1


Make a wedge from hardwood or plastic to hold the aperture lever in the open position. Make it no taller above the mount than the lever itself, and make it wider than the remaining slot opening so it cannot fall in. The return spring pressure and the lens adaptor will hold it in place.

It would look something like this.

enter image description here

  • \$\begingroup\$ Interesting!! I guess this is something I could pay somebody to 3D sculpt and print for me :O? \$\endgroup\$ Commented Feb 23, 2022 at 11:34
  • \$\begingroup\$ It would be small enough that it might not print that easily... I've had mixed luck with really small pieces and FDM printing. \$\endgroup\$ Commented Feb 23, 2022 at 13:29
  • \$\begingroup\$ @JamieHutber No need to be so fancy. Just cut the piece from cardboard. \$\endgroup\$
    – xiota
    Commented Mar 25, 2022 at 9:34

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