This was one of the finest lenses available at its time and even compared to today's standards it delivers excelent picture quality in terms of contrast, sharpness and distortion.

A short introduction to the probem this lens solved: A photographic lens is a device that catches light coming from objects and projects it onto light sensitive material. Each point in an object that is visible emits some light that divert into space. The lens grabs part of that light, that is divergent from each point in the object and forces them to converge into points on the film (or a digital sensor nowadays). Later, looking to the printed image, we will recognize the scene because bright and dark points of different colors will show a relative position and value very similar to what our eyes would have seen if they would be placed at lens standpoint the moment the picture was taken. Because our eyes are also lenses with light sensitive material behind.

I am saying that because the "anastigmats" have all to do with "points". Stigma means point in Greek. Astigmatism is an optical aberration that prevents a lens in forming points in the image out of points in the object. From the first Petzval lenses (~1840) it took some decades till lens makers discoverd a way to get rid of that imperfection.



In this illustration from Britannica on-line we see the unwanted condition. Light coming from point P converges in a peculiar way: the part painted in blue converges closer to the lens than the transversal part in orange (this has nothing to do with light color it is just an indication for easiness of diagram reading). Then we have a "circle of least confusion" but not a sharp point image of P. Wherever the film is placed, it is always a compromising position with some degree of unsharpness.



The first lens having astigmatism corrected was the Concentric from Ross (England), designed in 1888/92 by Schroeder, but it had a very low apperture about f/20. Already in 1890 Paul Rudolph of Zeiss succeeded, in producing Anastigmats with appertures of f/7.2 and f/4.5 in 1891.


From Lens Vade Mecum (referenced below)

The lens in this page folows the design above. It was issued by Zeiss in 1895 and belongs to the Anastigmats family. It is a 4+4 symmetrical lens and covers 80 degrees. Each half is corrected from astigmatism and can be used separatedly placed behind the iris.
In combination the foci is 300 mm (12 inches) and the apperture is f/7. Alone the cells have 19 1/4 inches (aprox 480mm) or 23 1/2 inches (aprox 587 mm) and the apperture becomes f/12.5. There is a ring with different apperture scales that can be rotated in order to have the lever indicating the right figure.



Many companies were licensed by Zeiss to produce this design:
Ross, London
Bausch and Lomb, Rochester, New York
Krauss, Paris - France
Fritch, Vienna - Austria
Koristcka, Milan - Italy
Suter, Basle - Switzerland

It is also known as Protar, name adopted by Zeiss when they lost their rights over Anastigmat and this became like a generic name. The specific contruction 4+4 is called Protar VII when cells were purchased separatedly and Protar VIIa when sold in sets, like this one. Ross engraved Zeiss Convertible Anastigmat, also a common description for this lens construction.



This is an original pair of yellow filters that came along with the lens. There is also a ring that I suppose should be used to allow intalling a filter when only one lens element is in place on the back of the barrel.

If you like lens history and design you should absolutely download the "A Lens Collector Vade Mecum" it is only 15,99 USD and an invaluable source of information. Go to: Lens Vade Mecum It has more than 700 pages with thousands of lenses description, pictures and diagrams.

Another excelent source is Rodolf Kingslake, A history of the Photographic Lens (Academic Press, INC. ISBN 0-12-408640-3)