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ABBE, ERNST (1840–1905)
German-born Ernst Abbe was one of the pioneers in op-
tical physics. In 1866, while a Professor at the University
of Jena, he met Carl Zeiss, later becoming Director of
Research at the Zeiss Optical Works in Jena.
Abbe and Zeiss later became partners (1875), and
were responsible for the development of many innova-
tive optical systems for the microscope, and for develop-
ments in optical design which were far-reaching—none
more so than the development, with Otto Schott, of the
world’s fi rst apochromatic lenses (1886), the fi rst to
eliminate chromatic aberration.
Abbe’s command of optical theory was a signifi cant
factor in the establishment of the worldwide reputation
of Zeiss optics, as all his lens designs were based on
precise, and theoretically sound calculations. Together
with Otto Schott, who he met in 1881, Abbe played a
signifi cant role in the evolution of new formulations for
the manufacture of optical-quality glass.
One of Abbe’s many signifi cant contributions to the
understanding of how lenses worked was his system
of ‘Abbe numbers’ which gave a numeric value to
the extent to which glass disperses light of different
wavelengths. These fi gures varied from around 25 for
fl int glass, to over 60 for crown glass—the lower the
number, the greater the loss of quality due to refractive
dispersion.
John Hannavy

ABDULLAH FRÈRES

Vhichen (1820–1902), Kevork (1839–1918).

and Hovsep (1830–1908)
Vichen Abdullah was an Ottoman Armenian who began
his photographic career touching up photographs at the
studio opened by Rabach in Istanbul in 1856. When his
brother Kevork returned from studying at the Murad-

Raphaelyan School in Venice in 1858, together with a

third brother, Hovsep, they took over Rabach’s studio,

which became known as Abdullah Fréres.

The brothers became offi cial royal photographers

after taking a portrait of Sultan Abdülaziz (1830–1876)

in 1863.

They took portrait photographs of Edward, Prince

of Wales, who visited Istanbul in 1869, and Empress

Eugénie (1826–1920) of France.

The Abdullah brothers were masters at both studio

and outdoor photography.

When the Ottomans were defeated in the Ottoman-

Russian War of 1877–1878, the Russian army made its

headquarters at San Stefano near Istanbul on 26 Febru-

ary 1878. Grand Duke Nicholas (1831–1891) commis-

sioned Kevork Abdullah to take a group photograph

of 107 people. Angered by this, Sultan Abdülhamid II

prohibited the brothers from using the royal monogram

and keeping the portraits of the sultan they had taken.

In 1866, at the invitation of the Khedive of Egypt,

Tevfi k Pasha, Kevork, and Hovsep opened a branch

studio in Cairo.

In 1890 Sultan Abdülhamid II restored the right of

the Abdullah brothers to use the royal monogram, and

the studio fl ourished once again.

In 1895 the brothers closed down the Cairo studio,

and at the end of 1900 they sold the Istanbul studio to

Sébah and Joaillier.

Engin Özendes

ABNEY, WILLIAM DE WIVELESLIE

(1843–1920)

English photographic scientist

Abney was born in Derby, England on July 24, 1843, the

eldest son of the Rev. Edward Henry Abney and Cath-

erina Abney (formerly Strutt). His father was the vicar of