Focus Rings

Rear lens caps · AirTag

Fujifilm X rear cap with an AirTag inside

A Fujifilm X rear cap with an Apple AirTag hidden in its base. The tag snaps in from the inside and stays out of sight, so a lens left on set or in a rental case shows up in Find My.

Make yours · €2.90Launch price, later €3.90
Fujifilm X rear lens cap with an AirTag snapped into its base, seen from the lens side

One part, no screws

The pocket wall is one closed ring. Three segments of it, joined at both ends and backed by a slot, flex as the AirTag passes and then keep pressing on it, so it clicks in and cannot shift. A notch lets you lift it out again with a fingernail.

Signal side out

The white side of the AirTag faces outwards behind a 1.2 mm face; the steel cover faces the lens. The lens keeps its full rear room.

Prints without supports

Every part of the ring grows from the layer below, nothing is printed in mid-air. Face down on the plate like every Focus Rings cap.

Same bayonet

Three claws sit in the lens gaps, so the cap goes on in one position. Then turn clockwise (looking at the face) about 40° until the lugs run onto the stops. The AirTag adds 7.3 mm of height and leaves the lens room unchanged.

Cut through the Fujifilm X AirTag rear cap: the AirTag held by the snap ring below the lens roomFace of the Fujifilm X rear cap with 23 mm as a two-colour inlay

Fits

  • Fujinon XF and XC lenses
  • Third-party X-mount lenses from Sigma, Tamron, Viltrox, Laowa, Samyang, TTArtisan and others
  • Lenses with a longer rear: choose Deep in the generator
Specifications
MountFujifilm X
Outside diameterØ52.0 mm
Height21.0 mm · Deep 26.0 mm
Room for the rear element11 mm below the rim; Deep: 16 mm
GripModule 0.8 gear (63 teeth) or flutes
AirTagApple AirTag, snap-in from the inside, no tools
Print orientationFace down, no supports
Print time (slicer estimate)about 41 min, about 14 g
Fit test ringIncluded with paid files, about 12 min
Files3MF (body + face inlay as one object), aligned STLs, printing guide

Print times are Bambu Studio estimates for an X1C with a 0.4 mm nozzle and 0.20 mm layers. Not every lens has been tested: check the fit before you print the whole cap.

Print and fit

  1. Print the fit test ring that comes with your files: the bayonet zone only, done in minutes.
  2. Put the lens lugs into the gaps and turn clockwise (looking at the face) until it stops. It should turn smoothly and sit firmly.
  3. Print the cap face down on the build plate, no supports. Two-colour faces: keep body and inlay as one object and give each part a filament.
  4. Press the AirTag in from the inside, white side towards the face, until the three tabs click.

Questions

How is the AirTag held without screws or glue?

By a closed snap ring: three segments flex slightly as the AirTag passes, then their nubs keep pressing on it above its widest point. If the click is too stiff or too loose on your printer, write to us and we send a different nub size.

Does the AirTag still work inside the cap?

AirTags work through plastic, and the white side faces outwards behind a thin face. Range depends on what is around the lens case, as with any AirTag.

Which lenses does the Fujifilm X AirTag cap fit?

Fujinon XF and XC lenses; Third-party X-mount lenses from Sigma, Tamron, Viltrox, Laowa, Samyang, TTArtisan and others; Lenses with a longer rear: choose Deep in the generator. Room for the rear element: 11 mm below the rim; Deep: 16 mm.

Has this Fujifilm X rear cap been tested on a lens?

Not yet on a Fujifilm X lens. The bayonet is measured from parts that fit real lenses and cameras, the lock is set just past the measured lug face like on our print-tested mounts, and every file passes a layer-by-layer support check. Check the fit first: your files include a fit test ring, the bayonet zone only, done in minutes. Print it and try it on your lens before you print the cap. Too tight or too loose? Tell us: the claws are adjustable.

Does it need supports?

No. The cap prints face down on the build plate. Every overhang is at most 50°, and the claws have sloped undersides that build up layer by layer.

Which filament should I use?

Rings without clamps and lens caps: PLA or PETG, 0.4 mm nozzle, 0.20 mm layers, your usual walls. PETG is a little tougher if the cap lives in a bag.

Why gear teeth on a rear cap?

They are the same module 0.8 teeth as our focus rings, so the cap matches your follow focus gear and grips well with gloves. The vertical teeth also hide layer lines. Prefer something smoother? Pick the flutes grip.

Other rear caps

All rear lens caps → · Focus gears by lens →