A bellows is basically an accordion-type tube that mounts between camera and lens (Novoflex model shown above). By moving the lens farther forward from the camera mount (lengthening the tube), you get closer focus distances (at the expense of infinity focus).
Typical macro lenses result in 1:2 (half-size), 1:1 (full size), or sometimes 2:1 (twice life-size) reproduction. At 1:1, a 36mm object would fill the 36mm width of the FX frame, for instance.
The question that often comes up for people working with small subjects is "how do I achieve greater than 1:1 reproduction ratios?" Simple: you add a bellows between the camera and lens. With a bellows setup, you can typically get up to 8:1 magnification with a ~100mm macro lens (a 4.5mm object fills the 36mm frame).
The following bellows are currently available for the Z mount:
- Fotodiox Macro Bellows [advertiser link] — US$60 — This simple, all-manual bellows is the least expensive way of extending macro focus at the moment. While it has a tripod mount, that's at the camera end of the bellows; I strongly recommend adding a plate across the two supporting bars, particularly if you're using a heavier lens, such as the Nikon 105mm f/2.8 S. If you try to use this bellows with a heavy lens via the tripod socket, you put pressure on the two guiding bars that will eventually cause issues. The Fotodiox bellows has no electrical contacts, so using it you'll be all manual, all the time. That's generally not a problem with static macro subjects. The Fotodiox is a low-cost option that is useful for those just beginning to explore extreme macro with static subjects, or who do extreme macro rarely.
- Novoflex Auto Bellows [advertiser link] — US$1289 — Much more expensive, this well-built system provides electrical contacts (via a coiled cable between the front of the bellows and the mount at the back), so supports all automated functions between camera and lens. It also uses a single plate rail, which I prefer for its structural integrity when using on a tripod. With the Nikkor macro lenses, this bellows is basically the Cadillac approach to extreme macro, but that comes at high cost.
