Komura 400mm f/6.3 (Bronica, Unihelicoid)
Sankyo Koki · Bronica S · 1965 · Long-focus lens head, 4 elements in 4 groups
Also known as: Komura 400mm f/6.3 Bronica · Komura 400mm F6.3 for Zenza Bronica · Sankyo Koki Komura 400mm f6.3 Bronica · Sankyo Kohki Komura 400mm F6.3 Bronica S2 · Komura 400/6.3 Bronica Unihelicoid · Komura Unihelicoid II 400mm f6.3 · Komura 400mm f/6.3 for Bronica S2 S2A EC · Zenza Bronica Komura 400mm f6.3 · コムラー 400mm F6.3 ブロニカ · コムラー 400mm F6.3 ユニヘリコイド · 三協光機 コムラー 400mm F6.3 ゼンザブロニカ用
Variants & identification
| Variant | Mount | Years | Serial ranges | Production |
|---|---|---|---|---|
| Komura 400mm f/6.3 head on Unihelicoid II (new large bayonet, Bronica C and later) | Bronica S, large bayonet of the C/C2/S2/S2A/EC (Unihelicoid II) | 1965 | — | — |
| Komura 400mm f/6.3 head on Unihelicoid III (old large bayonet, Bronica Z/D and S) | Bronica S, old large bayonet of the Z/D and S (Unihelicoid III) | 1965 | — | — |
- Construction (4 groups, 4 elements), manual diaphragm, the 67 mm screw-in attachment and the Unihelicoid II/III versions are from Japanese Wikipedia's Komura list on the ゼンザブロニカ page, which gives no years, prices, weights or close-focus figures for any Komura lens. camera-wiki's Bronica lens list gives '400mm f6.3 Komura (focus mod II)' without defining the term.
- Date: no source dates the Bronica Komuras. The year is approximate: a Unihelicoid II exists for the large bayonet that arrived with the Bronica C in December 1964, and Mike Eckman reproduces a 1965 EPOI dealer catalogue listing some forty Komura lenses from 28 mm to 800 mm, so the heads belong to the mid-1960s.
- Relatives: Japanese Wikipedia says the 300, 400 and 500 mm heads could also go on the Rollei SL66 with a Komura SL66 adapter, and that the lenses were later offered as head + helicoid + mount under the name コムラノンシステム67・35 for the Asahi Pentax 6×7, the Rollei SL66 and various 35 mm SLRs. Sankyo Koki's 400mm f/6.3 Komura for 35 mm cameras, on the 39 mm Unidapter mount, is the lens that forum users praise; whether it shares the Bronica head's four-element glass is not documented, and its reports are not carried onto this page.
- The コムラー テレモア66 X2 For BRONICA 2× converter sits between body and focusing unit and works on the S2 and EC series, but Japanese Wikipedia says it cannot be used with lenses that mount directly on the body bayonet, as the Unihelicoid heads do.
How to tell them apart
- A two-part lens: a Komura 400 mm f/6.3 head with a manual (non-preset) diaphragm and a 67 mm filter thread, and a separate Komura Unihelicoid focusing mount engraved II or III that carries the Bronica large bayonet; the mount's number, not the head, decides which bodies it fits
- Shares the 67 mm thread with the 300 mm head; the 500 mm head takes 77 mm (Japanese Wikipedia)
- The Unihelicoid mounts the large body bayonet directly with the Bronica's own focusing unit removed, where the 105 mm leaf-shutter Nikkor and the Nikon tele focusing units go, not on the small front bayonet of the standard lenses
- Not Nikon's Nikkor-Q 400mm f/4.5 head on the Bronica focusing unit, which carries Nippon Kogaku's name; not a Komura 400mm f/6.3 on a 39 mm Unidapter thread, which is the 35 mm-format lens
Komura 400mm f/6.3 head on Unihelicoid II (new large bayonet, Bronica C and later):
- A manual-diaphragm 400 mm head on a Komura focusing mount engraved Unihelicoid II, for the large body bayonet introduced with the Bronica C in December 1964 and kept through the C2, S2, S2A, EC, EC-TL and EC-TL II (Japanese Wikipedia)
Komura 400mm f/6.3 head on Unihelicoid III (old large bayonet, Bronica Z/D and S):
- The same head on a focusing mount engraved Unihelicoid III, for the old large bayonet of the Zenza Bronica Z/D and S, which is not interchangeable with the new one (Japanese Wikipedia)
- Komura 400mm f/6.3 head on Unihelicoid II (new large bayonet, Bronica C and later): One of two versions Japanese Wikipedia records for each of the 300, 400 and 500 mm heads: Unihelicoid II for the newer large bayonet, Unihelicoid III for the older. The same Unihelicoid takes all three heads. No source read for this page dates either mount or gives a price.
- Komura 400mm f/6.3 head on Unihelicoid III (old large bayonet, Bronica Z/D and S): Known from Japanese Wikipedia alone. The bodies it serves follow from the bayonet: the Z/D and S carry the earlier large-bayonet standard, the C and later the newer one.
Specifications
- Formula
- Long-focus lens head, 4 elements in 4 groups
- Construction
- 4 elements / 4 groups
- Aperture range
- f/6.3
- Filter
- 67 mm
- Years manufactured
- 1965
- Country
- Japan
What reviewers say
No reviews aggregated yet — this family is still in the research queue. Written one? We'd love to index it.
History
The Komura 400mm f/6.3 is the middle of the three long-focus lens heads Sankyo Koki made for the focal-plane Zenza Bronica, to be used on the maker’s Unihelicoid focusing mount in place of the camera’s own focusing unit. With the Bronica’s helicoid removed, the large bayonet on the body is exposed; the Unihelicoid carries that bayonet and takes the 300, 400 and 500 mm heads interchangeably, the same arrangement Nikon used for its long Nikkor heads on the Bronica focusing unit. Japanese Wikipedia gives the 400 as four elements in four groups with a manual diaphragm, rather than the preset ring of the 300, and a 67 mm screw-in filter thread, and records two versions: on the Unihelicoid II for the large bayonet that came with the Bronica C in December 1964 and stayed through the EC-TL II, and on the Unihelicoid III for the older bayonet of the Z/D and S, which is not interchangeable with it. camera-wiki lists it as “400mm f6.3 Komura (focus mod II)”, a term it never defines.
No date, price or weight for the Bronica head appears in any source read for this page; the mid-1960s placing follows from the Unihelicoid II’s bayonet and from the 1965 EPOI dealer catalogue reproduced by Mike Eckman, which already runs the Komura line from 28 mm to 800 mm. The heads outlived the Bronica: a Komura adapter put them on the Rollei SL66, and the lenses were later offered as head, helicoid and mount under the name Komuranon System 67/35, for the Pentax 6×7, the Rollei SL66 and 35 mm SLRs. Komura’s 2× Telemore 66 converter for the Bronica cannot be used with them, since it sits between body and focusing unit and Japanese Wikipedia excludes lenses that mount directly on the body bayonet.
There is a well-liked Komura 400mm f/6.3 for 35 mm cameras, a two-piece lens with a 39 mm thread for the Leica Visoflex and Komura’s Unidapter mounts, which forum users have found solidly built and far better than the cheap 400 mm lenses of its day. Whether its glass is the Bronica head’s four-element design is not documented, and the Bronica head itself has no review that has been found. A buyer should check which Unihelicoid the head comes on, that the manual diaphragm and helicoid turn freely, and that the 67 mm thread and the head’s bayonet into the mount are undamaged.
This history is AI-written, from the sources listed at the foot of the page. Where the record is silent it says so rather than filling the gap — but no human wrote these sentences.
Example photos
Sample photo wanted — shot with a Komura 400mm f/6.3 (Bronica, Unihelicoid)? We'd love to feature it (with credit).
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