Optical equipment, polarizing eyepiece, metal / glass, made by Carl Zeiss, Jena, Germany, [1890-1920], used at Sydney Observatory, New South Wales, Australia, [1890-1920]
Telescope eyepieces vary widely in size, focal length, and design. This polarising eyepiece was used with Sydney Observatory's 11.4 inch telescope (H9886) to make solar observations.
The 11.4 inch telescope was purchased in 1874 by Government Astronomer H. C. Russell for the upcoming Transit of Venus. The telescope had a clear aperture of 11.4-inches and a focal length 12 feet 6 inches and Russell commented that while this shortened focal length was a disadvantage to definition it was an advantage to its light catching power. This eyepiece, in conjunction with the 11.4 inch telescope, would have played an important role in recording solar observations at Sydney Observatory.
This eyepiece remains of national significance due to its pioneering role in Australian science and its association with Australia's earliest astronomers. It is also of international significance due to its association with nineteenth century scientific instruments and their makers.
Todd, David, P., Stars and Telescopes, Sampson Low, Marston, and Co., 1900
Russell, H., C., "Report of Astronomer for 1874 & 1875', New South Wales Government Printer, 1876
Written by Erika Dicker
Assistant Curator, February, 2008.
The eyepiece was made by Carl Zeiss in Jena, Germany between 1890 and 1920.
In 1846 Carl Zeiss (1816-1888) started his instrument making business in a small town of Jena in Germany. He quickly became interested in optics and by 1848 was making and designing microscopes. By 1866 Zeiss realised that to expand his business he needed someone with a greater understanding of optics. Zeiss found the right person in Ernst Abbe (1840-1905) and by 1870 they had devised a new way for computing the manufacture of optical lenses which would improve performance by eradicating much of the colour and spherical distortion of the lens.
In 1879 they produced the homogenous immersion objective but the flint and crown glass which they used to make their lenses needed to be improved before they could perfect their lenses. Optical glass made from silica, soda and potash was supplied by manufacturers who used the same recipes for much of the nineteenth century. It was only after Zeiss and Abbe teamed up with the glass maker Otto Schott in 1881 that they were able to produce a better quality glass without so much of the characteristic green or yellow tinges.
In 1886 Zeiss and Abbe produced the apochromatic (better colour correction than an achromatic) microscope lens. Consisting of ten lenses it effectively removed secondary spectra distortion and spherical aberration. Using the new glass and Abbe's formulas the Zeiss factory began producing their famed anastigmatic photography lenses in 1890. It was around this time that the Zeiss works began constructing eye pieces and objectives for telescopes.
Auerbach, F., The Zeiss Works and the Carl Zeiss Foundation in Jena, W. & G., Foyle, London, England, about 1925?
Written by Geoff Barker,
Assistant Curator, November 2007.
This polarising eyepiece was used with Sydney Observatory's 11.4 inch telescope (H9886), and used for solar observations.