Steve Cushing Impresionist Fine Art Photography

Embracing imperfection, recording emotions, one impression at a time…

Steinheil Munchen 13.5cm f/4.5 Unofokal Medium Format Lens and Compur Shutter originally mounted on a 10cm plate

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The Lens details of a series of images taken by Steve Cushing on mirrorless camera.


C. A. Steinheil Söhne Optical and Astronomical Works was a German optical company based in Munich (München), Bavaria. It made optical equipment and camera lenses from the 19th century until the 1970s. The company was founded in 1855 by Carl August von Steinheil (1801-1870), a German physicist and astronomer.

At the time of founding, the organisation was known as the Steinheil Optical Institute. The company made many of the astronomical telescopes for German observatories include those at Upsala, Mannheim, Leipzig, and Utrecht.

Carl's son Hugo Adolph Steinheil (1832-1893) bought out father's interest in the Institute, renamed it to C. A. Steinheil Söhne and continued as owner of the company after his father's death in 1870. In 1866 it invented the Aplanat lens. In 1890, Adolph's son, Rudolph Steinheil (1865-1930), joined the family business, eventually become owner in 1892. During the early years, the company referred to itself as C. A. Steinheil Söhne but was commonly known simply as Steinheil. In the 1930s, Steinheil became a stock company and was jointly owned by Rudolph Steinheil's five daughters.

In 1893 the orthostigmat was constructed, a symmetrical, cemented anastigmat (light intensity 1: 6.8). The symmetrical, non-cemented anastigmat Unofocal is the next important development in 1903. With the Triplar, Steinheil then brought out a comparatively bright portrait lens in 1908 (light intensity 1: 3.8); the Cassar triplets sold in the 1920s already have light intensities of up to 1: 3.5 - for film cameras even up to 1: 2.5.

In the course of time, the previous production lines (astronomical, spectrographic and photographic optics) were expanded to include the manufacture of optical glass. Steilheil was able to devote himself to the special challenges for high-speed camera and large astronomical lenses. After completing his studies, the later well-known optics designer Heinrich Erfle worked at Steinheil from 1907 to 1909.

At the end of the 1930s the company was renamed Optische Werke C. A. Steinheil Söhne GmbH. [2] The company was then - as is often the case in the optical industry - continued as a family business.

Steinheil has been producing target devices for combat aircraft in the Austrian municipality of Lustenau since autumn 1939. From the spring of 1942 to 1945, the company employed forced laborers from a camp set up in the community

Steinheil made a few cameras at various times, and during the late 1940s, it developed an advanced 35mm camera with interchangeable lenses, the Casca.

On 24 Oct, 1952 C.A. Steinheil filed for a United States trademark on the word Steinheil. The trademark registration was granted on 23 March, 1954. At the time of filing L. F. Von Hornstein was listed as the Director of the company and the address was listed as St. Martinstrasse 76, Munich 8, Germany. The company name on trademark filings in the 1950s was shown as Optische Werke C. A. Steinheil Sohne GmbH. The trademark application states that the name Steinheil was first used in commerce in 1884.

This Lens

It is hard to get much information on this lens the only data I found said "This was the "new" anastigmat in the 1906 adverts. and it was a good one. One with all the glasses of about the same focus- more interesting perhaps was that the inner glasses become more close together than was usual in this type".

It is a kind of Dialyte. It got the name from the special construction with all four elements having the same focal length - two positive, and two negative. That didn't last long though, since it was quickly found that using slightly different focal lengths made a better lens. But the name stuck.

A dialyte lens (sometimes called a dialyt) is a compound lens design that corrects optical aberrations where the lens elements are widely air-spaced.

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The design was used to save on the amount of glass used for specific elements or before elements were cemented as shown on the left (2) because old lenses had dissimilar curvatures as shown and were not cemented together.

The word dialyte means "parted", "loose" or "separated".

Cemented lenses came about to avoid aberrations caused by a single lens as shown on the right.

There are many types of dialyte camera lenses. One type is a symmetrical design consisting of four air spaced lenses: the outer pair is biconvex and the inner pair is biconcave. The symmetrical structure provides good correction for many aberrations as shown on the left.

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The Aviar type of lens (Taylor Hobson) is similar but is considered to have a different origin, from the splitting of the central biconcave element of the Cooke triplet. The resulting two biconcave elements are closer together than in the Dialyte/Celor design.

It is a large frame lens and that has its complications on a full frame camera due to the image circle.

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Some of the lenses used on this site are large frame. That is 4 x 5

Since the aspect ratio of 4x5 film is different than 35mm and full frame sensor, it makes comparison a little less than exact. In general, you sort-of multiply the 35mm focal length by three to get close to a similar angle of view with a 4x5 lens. Here's some common large format focal lengths and their approximate 35mm equivalent.

23mm would be 75mm on 4x5

28mm would be 90mm on 4x5

45mm would be 135mm on 4x5

Or if we are using full large frame on a 35mm camera……..

150mm from a 4x5 camera will be 450mm equivalent on a full frame

200mm from a 4x5 will be 600mm field of view on a full frame sensor………

But what is the issue then and why are large frame lenses not as fast as 35mm lenses?

The problem is when we adapts a large format lens to a small camera, only a fraction of its actual image is captured. A 200mm lens designed to work in 4x5, when installed in a 35mm full-frame camera (24x36mm), will deliver the same framing of a scene that a native full-frame 200mm lens would do. But we are cropping the field of view so we have a 600mm equivalence so the images are not really comparable. It terms of pixel perfect lovers a lousy lens design made for small format will probably outperform the quality of a magnificent optic made for large format. Of course for me as an artistic photographer the imperfection is what makes a lens interesting.

The point is that in a lens concept, the focal length and image size are not inherent to that concept. Lenses are scalable. If you double all dimensions you double the focal length. What is absolute and really defines a lens concept is the angle of view and maximum aperture. And it is far more difficult to produce a lens with a broad angle of view than a narrow one. The consequence is that a large format lens will not work as a long-focus lens for a 35mm format.

In order to open the angle of view for a given lens concept, the lens designer has to sacrifice something else. The most obvious is the aperture and that indeed improves the overall image quality at the expense of darkening it.

Another option is to admit a larger circle of confusion for that design. circle of confusion (CoC) is related to the size of a point on the scene that is never rendered as an ideal point, but rather as a small surface on the image. The CoC is the diameter of that surface when seen as a disk.
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So the industry understands that while 24x36mm needs a circle of confusion around 0.0029mm, an 8×10” format can perfectly live with something 7.5 times bigger, like 0.22mm. That is why a fraction of an 8×10” image will present much lower quality when printed with the same enlargement of the same image originally done in 24x36mm format. However the circle size does have one big advantage, and that is the ability to use the lens on a shift/tilt adapter, and to me this allows for lots of creative freedom.

Lens In Use



For images using this lens click HERE

For general information on lens design and lens elements go to the homepage HERE

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