Rolleiflex and Rolleicord bayonets: identify Bay I, II and III
Identify your Rolleiflex or Rolleicord and its accessory mount using the serial number. Model search for Yashica and Minolta, diagrams and practical checks before buying.
Which filter, lens hood or Rolleinar fits your Rolleiflex or Rolleicord? Bay I, Bay II and Bay III are not interchangeable. Use the finder below to identify a model from its serial number, then check the accessory fitting. This guide also covers several Yashica models and the Minolta Autocord: not every twin-lens reflex (TLR) camera has a bayonet mount.
1. Identify your camera’s accessory mount
Not sure which model you have? Start with its serial number. For a Rolleiflex or Rolleicord, include any engraved prefix: “Vb 2 610 000”, “T 2 205 000” or “3.5F 2 205 000”. The finder looks for a documented serial range, identifies the corresponding model and displays its mount. The model field is optional and can help resolve an ambiguous match.
CAMERA IDENTIFIER Enter your Rollei serial number to find its model and accessory mount. You can also search by model, including Yashica and Minolta. Rollei serial ranges documented by Rolleigraphy, checked on 14 September 2026. Coverage is not exhaustive; newer cameras with coded numbers cannot be identified by serial number alone. Your entries stay in your browser.Which bayonet fits your TLR?
When there is a single documented match, the result appears directly. If several models are possible, the finder lists them and indicates whether they share the same mount. Serial ranges come from Rolleigraphy, by F. W. Stutterheim, including tables based on Claus Prochnow’s work. They are not certificates of authenticity. Yashica and Minolta searches remain model-based. No result does not mean “no bayonet”.
Where should you look for the number?
The serial number is usually on the body, near the nameplate, or below the taking lens on some series. Do not accidentally use the lens serial number. Exception: on some early Rolleicord I, Ia and II cameras, the official number is the one on the lower lens. Select the early-Rolleicord lens-number option in the finder. DRP, DBP, DRGM and DBGM are industrial-property markings, not serial numbers.
A serial number may identify a series without establishing a Whiteface finish, special edition or Planar/Xenotar lens variant. For GX, FX, FX-N, FW and FT cameras with coded numbering, enter the model: the factory index described by Rolleigraphy is not a complete public model-identification table. Missing serial ranges are not invented.
2. Bay I, Bay II or Bay III: the useful reference points
On a TLR, the lower lens exposes the film; the upper lens is for viewing. Read the lens name, focal length and maximum aperture on the lower lens. The table summarises common families: always check the exact version.
| Camera or family | Mount | What to check |
|---|---|---|
| Rolleiflex 3.5 X / A (MX) / B (MX-EVS) / T | Bay I | Pre-war Automat cameras have earlier fittings |
| Rolleicord III to Vb | Bay I | Rolleicord II depends on the version: model 1 has no bayonet |
| Rolleiflex 3.5 E / E2 / E3 / F | Bay II | 75 mm f/3.5 Planar or Xenotar |
| Rollei Magic / Magic II | Bay II | An exception despite the f/3.5 Xenar |
| Rolleiflex 2.8 B to F | Bay III | The 2.8 A is a special case |
| Early Tele-Rolleiflex | Bay III | 135 mm f/4 Sonnar |
| Early Wide-Rolleiflex / FW / FT | Bay IV | Check accessories specifically intended for the model |
| Rolleiflex 2.8 GX / FX | Bay III | Do not confuse FX with FX-N |
| Rolleiflex FX-N | Outer Bay IV | No inner bayonet; a suitable adapter is needed for a filter |
| Yashica Mat-124 / Mat-124G, D, 635 | Bay I | Check hood fit and clearance |
| Minolta Autocord | Bay I | Check accessory tolerances |
| Yashica A / B / 44A | Push-on | 32 / 36 / 28.5 mm respectively |
Useful examples to remember: 3.5 F → Bay II; 2.8 F → Bay III; Rolleiflex T → Bay I. The aperture “f/3.5” alone is not enough. B30, B34 and B38 markings found in listings are family references: also ask for the explicit Bay I, II or III designation.
3. Understanding the two fittings in the diagram
A double bayonet means two accessory fittings around the same lens, not the camera’s two lenses. The inner fitting normally takes a filter or supplementary lens; the outer fitting takes the lens hood. A suitable combination allows a filter and hood to be used together. This describes the common double-bayonet arrangement: early generations and the FX-N are exceptions. The finder does not show a misleading modern drawing for an older fitting whose profile is insufficiently documented.
How should you read the dimensions? The pairs ≈ 30/37 mm, 34/41 mm and 38/46 mm shown by the finder are documentary reference values for Bay I, II and III. Manufacturers and sellers do not always measure the same seating surface. These values specify neither tolerances, locking profiles nor screw threads. Undocumented dimensions for Bay IV and the 2.8 A are not invented.
A Rolleinar is used for close-up photography. Check the contents of the set and the parallax-correcting component for the viewing lens, as well as the bayonet size. Components differ between generations: a single close-up lens is not necessarily a complete set.
Exceptions that help avoid mistakes
- Rolleiflex 2.8 A: a special mount. A standard “Bay II” listing does not establish compatibility; ask for explicit confirmation for the 2.8 A.
- Original Rolleiflex: 24 mm push-on fitting on the taking lens and 28.5 mm on the viewing lens. Early Standard models, early Rolleicords and pre-war Baby cameras also have particular fittings: do not automatically apply the rules for later double bayonets.
- Rolleiflex 4×4 and Yashica 44: format and hood clearance also matter. A “Bay I” result does not make every hood interchangeable.
- Yashica: watch for models without a bayonet. A push-on accessory does not lock like a Bay I accessory.
Before buying: four simple checks
- Note the complete reference: camera plus mount. The finder’s copy-reference button lets you pass this information to a seller.
- Ask for useful photographs: the accessory marking, rear view and fixing mechanism. A front view alone is not enough.
- Check clearance: space between the two lenses, hood fit with a filter installed, and possible vignetting if an adapter is added.
- Try it without force: the lugs should engage and lock without excessive effort. Stop if the accessory resists.
An adapter can accept a modern screw-in filter, but check both ends: the camera-side bayonet and the filter-side thread. “37 mm”, for example, is not enough to identify a Bay I accessory.
Frequently asked questions
I only have the serial number. Is that enough?
Often, yes: if only one series matches, the model and mount appear directly. However, 2 205 000, for example, occurs in both T and 3.5 F series: the engraved T or 3.5F prefix distinguishes them. For newer models with coded numbers, the available documentation does not reliably identify the model from the number alone.
The filter has the right diameter, but it does not fit. Why?
A diameter does not describe the attachment system. Bayonet, push-on and screw-thread fittings are different; lug profiles and tolerances also matter. Never try to overcome an incompatible fitting by forcing it.
My camera is not listed
Coverage is limited to the models documented in this version. Note the model designation, inscriptions on the lower lens and body serial number. Photograph the front and the mount for manual identification.
Still unsure? Contact HostoPhoto with the model name and photographs of the camera and accessory. These are more useful than a diameter measurement alone.
Sources and limitations
Guide reviewed in September 2026. Detailed sources for each result are available in the finder. The diagrams are original drawings based on photographs of real rings, visually isolated from the camera body and glass. Their simplified outlines are not engineering drawings.
- Rollei accessory catalogue, 1961–1962: accessory families and uses.
- Ausgeknipst: Rolleiflex models and bayonets: overview and exceptions.
- Rolleigraphy: identification and serial-number ranges, including the 3.5, 2.8, Rolleicord, T, 4×4, Tele, Wide and Rolleimagic tables. The main source for serial-number searches; notes and overlapping ranges are retained.
- Yashica TLR: accessories and mounting variants.
- PhotographyAttic: dimensional references for Bay I, II and III accessories.
- Minolta Autocord instruction manual.
Photographic references for the silhouettes: a detached Rolleicord Vb front plate (Bay I), Rolleiflex 3.5 F (Bay II) and Rolleiflex 2.8 F (Bay III), Leitz Photographica Auction. Third-party photographs are not reproduced in this guide.
