NB: This is a draft article with a number of omissions and content to be added. If you have any in-depth information, or original manufacturer manuals, catalogues or period advertisements that might be relevant, please email Mark here. Peer review and contributors welcome, and will be credited. Similarly, if you have any memorable images shot with these lenses, we’re happy to show them in our gallery with a link to your social media or website.
SERIAL NUMBERS
| SERIALS | PRODUCTION DATE |
| 23 – c.17,000 | 1896-1911 |
| c.17,000 – 104,857 | 1911-1915 |
| 104,857 – 114,600 | 1915-1923 |
| 114,738 | 1924 |
| 122,831 | 1924 |
| 125,199 | 1925 |
| 160,120 | 1926 |
| 160,120 – 221,722 | 1926-1933 |
| 221,722 – 279,800 | 1933-1939 |
| — | 1939-1945 (military production outside main sequence under separate serial numbering system associated with English National Optical Co, Leicester) |
| 279,800 | 1946 (Deep Field Panchro) |
| 298,690 | 1947 (first Amotal) |
| 300,540 – 384,391 | 1947-1950 |
| 386,936 – 390,395 | 1951 |
| 458,392 | 1952 |
| 458,378 | 1953 |
| 470,382 – 474,899 | 1954-1955 |
| 516,882 | 1956 |
| 562,153 | 1960 |
| 579,604 | 1962 |
| 580,000 – 620,000 | 1962-1965 |
| 620,000 – 700,000 | 1965 – Ental II still in production? |
| 705,305 | After 1971 |
| 775,996 | After 1975 |
| 787,521 | After 1981 |
| 788,501 | After 1983 |
| 788,649 | After 1987 |
After 1910 “By H.D. Taylor’s Patents” was no longer engraved on the lenses.
By 1926, the 2.5 inch, Series VIIb was no longer made and by 1956, the 8 inch version was dropped.
The Series VII never appeared after 1910 (but in 1909 catalogue).
Series VIa after 1930 (until c.1947).
Series VI f5.6 from 1908 – c.1930
By c.1915, the 4.25, 5, 5.5, 6, 7.5 and 9 inch Series V f8 Process lenses were no longer being made but the 11, 13, 16, 18, 25 (f/10), 30 (f/16) and 36 (f/16) focal lengths were available. About 1921, only the 11, 13, 16, 18 and 25 (f/10) were offered.
Series IV f5.6: From 1908 through c.1921, the Series IV, f/5.6 was offered in eight focal lengths from 5 through 18 inch. By c.1924, it was limited to 8, 15.5 and 18 inch focal lengths. By the end of 1926, the Series IV 15.5 inch lens was discontinued.
Latest Ental serial: 584576 (50mm) / Earliest Ental II serial (82mm): 588835. If changeover late 1960 ‘according to sales leaflet’ VM . . . ?