Bis-Telar

1905

Rathenow Optische-Industrie Anstalt vorm. Emil Busch

Rathenow

Germany

Series II No. 3. f7, 16"

Lens Type:

Telephoto.

Iris diaphragm to f64. Black painted mount. 8 ¼" bellows extension. For half-plate.

Series III No. 3. f9, 14"

Iris diaphragm to f45. Brass mount. 8 ¼" bellows extension. For half-plate.

Serial Number:

201475 (c. 1910) .

The Bis-Telar, designed by K. Martin, was the first fixed separation telephoto lens. Two series were produced:

The first for general use with an aperture of f9 giving a 1 ⅔ magnification in focal lengths from 7 - 14".
The second (c. 1908) at f7 in lengths of 8 - 22" for up to whole-plate.

The Bis-Telar was available as lens cells to be fitted each side of a leaf shutter. A third series was for aerial photography with an aperture was f9.

References & Notes:

BJA 1906, p. 439. BJA 1907, p. 869. BJA 1909, pp. 369, 697. BJA 1910, p. 356. BJA 1911, p. 361. BJA 1912, pp. 382, 719. Kingslake, p. 137.

Early Photography