Cooke Aviar 15.2cm (SKa 4)
Taylor, Taylor & Hobson · Hasselblad Ross · 1942 · 152mm f/4.5 · Aviar (Cooke)
single source, unconfirmedAlso known as: Cooke Aviar 15.2cm (SKa 4) · Ross SKa 4 152mm
Variants & identification
| Variant | Mount | Years | Serial ranges | Production |
|---|---|---|---|---|
| SKa 4 bayonet | Ross SKa 4 (its own bayonet — hand-fitted to one camera) | 1942 | — | — |
- No serial number for a 15.2cm Cooke Aviar in Ross SKa 4 mount has been published anywhere consulted, and no serial list has been published for the lens. Hasselblad Historical, the only substantial source on the Ross cameras, marks several of its specifications as information requested.
- Delta Lenses' Taylor-Hobson serial timeline, the fullest published, is headed by its author as a draft and incomplete article inviting correction, and it is a reconstruction from observed lenses rather than a factory list.
How to tell them apart
- Bought in from Germany during the war — Ross built the bodies and the shutters in Göteborg but made no glass
SKa 4 bayonet:
- Uncoated: Ross fitted no anti-reflection coating to any of its lenses
- The protective barrel is engraved with the serial number of the camera it was fitted to — mounts were hand-tuned individually, so a lens does not necessarily fit another body of the same model
Serial-range notes
- the number on the barrel
- The rule, and it is not a dating rule. The number engraved on the protective barrel is the serial of the SKa 4 body the lens was hand-fitted to, not the lens's own, so it identifies which camera the lens belongs with and says nothing about when the glass was made. A lens separated from its body cannot be matched to another of the same model by that number, and cannot be dated by it either.
- no factory record exists
- Cooke Optics states plainly that the books no longer exist for Cooke lenses made before 1947, which puts a 1942 Aviar beyond any serial-to-year lookup at source. The compendium offers dated sample lenses for comparison in place of a table, and no sample for a 15.2cm Aviar of this period has been published.
- leading zeros, and the TT prefix
- What a wartime Taylor, Taylor & Hobson number looks like, if one is found. Delta Lenses records that from 1939 to 1945 the firm's military output ran outside the main sequence, on a separate numbering associated with the National Optical Company of Leicester; those numbers are often seen with a leading zero, as in 08791 and 025880. Some Air Ministry lenses instead carry a TT prefix on numbers within the main sequence — an Anastigmat 20-inch f/5.6 Aviar is recorded as TT248911 against Air Ministry contract 14A/2271. The main sequence itself had reached about 221,800 to 279,700 across 1933 to 1939.
Specifications
- Formula
- Aviar (Cooke)
- Aperture range
- f/4.5
- Country
- Germany
- Coating
- None — uncoated
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 one British lens in the Ross line, and a reminder that a neutral country buys where it can. Hasselblad Historical lists a 15.2cm Cooke Aviar among the SKa 4’s lenses alongside the 15cm Zeiss Tessar, so the camera appears to have had two options at about the standard focal length — one German, one from Taylor, Taylor & Hobson of Leicester.
Ross Aktiebolag of Göteborg was the company Victor Hasselblad ran through the war, building aerial cameras for the Swedish air force, and it is where the firm that later made the 1600F learned its trade. Ross built the bodies and, unusually, the shutters; it made no glass at all. The lenses came from Germany — Zeiss, Schneider and Hugo Meyer — and Hasselblad Historical notes that no documentation has been found describing how they were imported into a neutral country that badly needed optics and rather more badly needed to be left alone. That account names Zeiss, Schneider and Meyer as the German suppliers and says nothing about how a Cooke lens reached Göteborg, which during the war is a question with an interesting answer nobody has published.
The Aviar is Horace Lee’s design of 1919, made for aerial survey from the beginning — four elements in four groups, corrected for flat field and low distortion, which is exactly what a mapping camera needs and what a Tessar of the same focal length gives away.
Nothing Ross fitted was anti-reflection coated; coating reached Swedish military optics after the war, and these lenses date from before it.
Hasselblad Historical’s account of the Ross cameras is the only substantial source on them, and its author marks several specifications as information requested — an open call to readers for detail he does not have. Maximum aperture, weight, element count and production quantities for this lens are among the figures that no published source gives, so what is recorded here is deliberately short. The aperture recorded here is the Aviar’s usual f/4.5 rather than a figure the source confirms for this example.
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 Cooke Aviar 15.2cm (SKa 4)? We'd love to feature it (with credit).
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