Komura 500mm f/7 (Bronica, Unihelicoid)
Sankyo Koki · Bronica S · 1965 · Long-focus lens head, 4 elements in 4 groups
Also known as: Komura 500mm f/7 Bronica · Komura 500mm F7 for Zenza Bronica · Sankyo Koki Komura 500mm f7 Bronica · Sankyo Kohki Komura 500mm F7 Bronica S2 · Komura 500/7 Bronica Unihelicoid · Komura Unihelicoid II 500mm f7 · Komura 500mm f/7 for Bronica S2 S2A EC · Komura 500mm f8 Bronica · Zenza Bronica Komura 500mm f7 · コムラー 500mm F7 ブロニカ · コムラー 500mm F7 ユニヘリコイド · 三協光機 コムラー 500mm F7 ゼンザブロニカ用
Variants & identification
| Variant | Mount | Years | Serial ranges | Production |
|---|---|---|---|---|
| Komura 500mm f/7 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 500mm f/7 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 77 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. The 500 is the only Bronica Komura head on a 77 mm thread; the 300 and 400 take 67 mm.
- Maximum aperture, disputed. Japanese Wikipedia and the owner's lens photographed on Monaghan's Bronica pages give f/7, and Sankyo Koki's 500 mm for 35 mm cameras is also an f/7; camera-wiki's Bronica lens list has '500mm f8 Komura (focus mod II)'. Stronger: f/7, which is what the engraved lenses read; the f/8 is unexplained and may be a transcription slip or a different listing of the same head.
- Construction against the 35 mm-format lens. Mike Eckman's Komura 500mm f/7 on the Unidapter mount is, by his count, 4 elements in 2 groups with a 16-blade diaphragm closing to f/45, 77 mm filters, 8 m closest focus and 1,653 g; Japanese Wikipedia gives the Bronica head as 4 elements in 4 groups. Whether the two share their glass, and whether one of the two element counts is wrong, is not settled by any source read for this page. Eckman notes that a version 'specifically designed for the Bronica medium format SLR' existed but does not describe it.
- 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 the 35 mm-format 500mm f/7 appears in the 1965 EPOI dealer catalogue Eckman reproduces, at $175 with Unidapters at $4.95 each; that price is for the 35 mm lens and not the Bronica head.
- 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. The コムラー テレモア66 X2 converter 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 500 mm f/7 head with a manual (non-preset) diaphragm and a 77 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
- The 77 mm thread sets it apart from the 300 and 400 mm heads, which take 67 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-P 600mm f/5.6 or Nikkor-Q 400mm f/4.5 heads for the Bronica focusing unit, which carry Nippon Kogaku's name; not a Komura 500mm f/7 on a 39 mm Unidapter thread with a tripod socket behind its middle bayonet, which is the 35 mm-format lens Mike Eckman reviewed
Komura 500mm f/7 head on Unihelicoid II (new large bayonet, Bronica C and later):
- A manual-diaphragm 500 mm head with a 77 mm filter thread 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 500mm f/7 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 500mm f/7 head on Unihelicoid II (new large bayonet, Bronica C and later): One of the two versions Japanese Wikipedia records for each of the 300, 400 and 500 mm heads. An owner's lens photographed on Robert Monaghan's Bronica pages is described as usable on the S, S2A, EC and EC-TL through its Unihelicoid, which does not say which Unihelicoid it carried. No source read for this page dates the mount or gives a price.
- Komura 500mm f/7 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/7
- Filter
- 77 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 500mm f/7 was the longest lens Sankyo Koki made for the focal-plane Zenza Bronica and the longest of its three Unihelicoid heads. Like the 300 and 400 mm it is a lens head with no focusing of its own, made to go on Komura’s Unihelicoid focusing mount, which carries the Bronica’s large body bayonet and fits once the camera’s own focusing unit is removed, the way Nikon’s long Nikkor heads go on the Bronica focusing unit. Japanese Wikipedia gives it as four elements in four groups with a manual diaphragm and a 77 mm screw-in filter thread, the only Bronica Komura head on that size, and records two versions: on the Unihelicoid II for the large bayonet that arrived with the Bronica C in December 1964 and continued through the EC-TL II, and on the Unihelicoid III for the older bayonet of the Z/D and S, which the new one does not accept. An owner’s lens photographed on Robert Monaghan’s Bronica pages is noted as usable on the S, S2A, EC and EC-TL through its Unihelicoid.
Its aperture is the one point sources dispute. Japanese Wikipedia, the lens on Monaghan’s page and Sankyo Koki’s 500 mm for 35 mm cameras all say f/7; camera-wiki’s Bronica lens list says “500mm f8 Komura”, with no explanation. The engraved lenses read f/7, and that is the better evidenced figure. There is also a gap between the Bronica head and its 35 mm-format relative that no source closes. Mike Eckman’s 2022 test of the Komura 500mm f/7 on the Unidapter mount, a two-piece aluminium lens of 1,653 g with a 16-blade diaphragm closing to f/45 and a closest focus of 8 m, counts its glass as four elements in two groups, against the four groups Japanese Wikipedia gives the Bronica head; Eckman records that a version made specifically for the Bronica existed but does not describe it. The 1965 EPOI dealer catalogue he reproduces priced the 35 mm lens at $175, with Unidapters at $4.95 each; no price for the Bronica head has been found, and no source dates it beyond the mid-1960s that the Unihelicoid II’s bayonet and that catalogue imply.
Eckman found the 35 mm lens sharp across the frame with contrast “a little on the low side”, and thought that for the money “this is a heck of a lens, it’s not perfect, but it doesn’t have to be”; whether any of that carries over to a 6×6 negative through the Bronica head is untested, since no review of the Bronica lens has been found. The heads also went on the Rollei SL66 through a Komura adapter, 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, as it sits between body and focusing unit and Japanese Wikipedia excludes lenses that mount directly on the body bayonet. A buyer should first establish which Unihelicoid the head comes on, since a III will not fit an S2 or EC and a II will not fit an S, then check that the manual diaphragm and the long helicoid turn freely, that the 77 mm thread is clean and that the head locks into the mount; a 500 mm head without its Unihelicoid cannot be focused on a Bronica at all.
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 500mm f/7 (Bronica, Unihelicoid)? We'd love to feature it (with credit).
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