A "Flatbed" Digital Shift Camera
The Rm3di is the portable flatbed digital technical camera of the Arca-Swiss R series (R-Line): instead of a bellows, it uses a rigid flatbed body plus helical focusing, and renders the shift and tilt between lens and back as fully geared controls. It is designed specifically for medium-format digital backs and mirrorless, and excels in particular at wide-angle shift (architecture, product, commercial).
The "3d" in the name refers to three-dimensional control over three classes of compositional movement — rise/fall, shift, and tilt. It is the digital successor to the earlier Rm3d.
Movements: All-Geared Self-Locking + AIP In-Image-Circle Shift
Every movement on the Rm3di is geared, micro-metric, self-locking, and graduated: it locks the moment you let go, and the readings are repeatable:
Shift ±15mm · Rise 30mm — the body can rotate 180° to convert the rise travel into a larger fall, for flexible allocation.
Built-in geared tilt / swing ±5° — tilt is built into the body, so no separate lens tilt adapter is needed. This is one of the Rm3di's conveniences relative to a bellows camera.
AIP (all-in-plane) in-image-circle shift — rise/fall and shift move only the back; the lens stays put, perspective is unchanged, and all of the movement stays within the lens's image circle. This is especially helpful for in-image-circle multi-frame stitching.
Specs & Mount
| Item | Rm3di |
|---|---|
| Type | Flatbed digital technical camera |
| Shift | ±15 mm, geared self-locking |
| Rise / fall | Rise 30 mm; rotate body 180° for greater fall |
| Tilt / swing | ±5° built-in geared (no lens tilt adapter required) |
| Focusing | Integrated helical focusing |
| Lens mount | Arca-Swiss R-mount (bayonet lens board) |
| Lens coverage | Approx. 23–210 mm |
| Format | Up to 6×9; takes 150MP backs |
| Weight | ~1070 g (2.36 lb) |
| Dimensions | Approx. H 20.8 × W 19.6 cm (incl. feet / grip / finder mount) |
Compatibility: Backs & Lenses
Digital backs / bodies (via a 6×9 adapter plate) — Phase One IQ (with X-Shutter lenses, the IQ4 experience comes close to a Phase One XT; but the body has no shutter button and writes no shift metadata), Hasselblad H, Mamiya 645 / Phase One, plus mirrorless such as the Fuji GFX 50R (mountable via adapter); 6×9 film backs are also supported.
Lenses — uses Arca-Swiss R-mount technical lenses (corresponding to the Rodenstock / Schneider digital large-format lens systems), covering roughly 23–210mm, with the wide-angle range as its home turf.
Rm3di vs Pico: Flatbed vs Bellows, How to Choose
Many people will line up the Rm3di against the Pico. First, to be clear: these are two portable digital technical cameras at the same tier in different forms, not a hierarchy of "which one is more advanced."
In one line: want out-of-the-box built-in geared tilt + a complete set of precision geared movements → Rm3di; have a mixed bag of medium-format lenses, want bellows flexibility, and tilt is optional → Pico. (For the Pico, see our other piece, "Arca-Swiss Pico: Shift in Your Pocket.")
Hands-On Workflow: How to Shoot Digital Shift
Pairing the Rm3di with Optaxis
The Rm3di's all-geared, readable movements are a perfect fit for "calculate first, then dial":
Scheimpflug tilt calculation — work out how much tilt you need, then dial it in precisely with the body's ±5° geared tilt.
Shift coverage check — based on the R-mount lens's image circle, verify whether shift ±15 / rise 30 still lands within the image circle without corner fall-off (especially useful for AIP stitching).
Gear-library logging — log the Rm3di + each R-mount lens + back as one kit, so stitch planning and exposure compensation are clear at a glance.
A one-kilogram flatbed that makes digital large-format shift "ready out of the box" — understand it, and you'll see why wide-angle architecture and commercial photographers favor this "flatbed."