Heinrich Ernemann in 1850 owned a shop for linen goods, trimmings and stockings in Dresden. In 1889 he and his Partner Mr. Matthias founded Dresdner Photographische Apparate-Fabrik Ernemann & Matthias.
Around 1890 the company started to run steam engines. 1891 Matthias left the company. Ernemann was self-educated about photography and talented for getting into that business. The first products of his company were wooden cameras for professional photographers. Until 1896 the company's own production of camera parts covered mainly the wooden parts, other parts had to be bought from suppliers. Then Ernemann added four new departments for camera parts production. The booming camera industry in Dresden led to a period of overproduction. Heinrich Ernemann knew how to get through the crisis: he transformed his factory to a stock market company, the Heinrich Ernemann, Aktiengesellschaft für Cameraproduktion in Dresden, founded in 1899. It produced cameras and movie projectors in Dresden and Görlitz. It took over the camera maker Ernst, Herbst & Firl and continued its Globus camera series. From 1901 to 1907 it was exclusive maker of Stöckig's Union cameras. Later it used that brand itself.
In 1907 Ernemann introduced its first SLR camera. In 1908 it started making its own lenses. Until then it had purchased lenses from Carl Zeiss and Goerz. Before the first world war, Ernemann employed Johan Steenbergen, who later founded Ihagee, also in Dresden. During the war Ernemann partially switched to production of warfare goods like its machine-gun camera and found many new customers for its "civil" vest pocket cameras among the soldiers.
So this is a review of the legendary "Ernostar 2/100" Lens, 1924 Ernemann, Dresden, no. 150452. The classic lens, early item with open helical. Let's think about this lens design conceptually. If we add a positive lens to the front side, the two positive lenses increase in overall optical power about the stop, so that means that the distortion becomes more difficult to correct. The last positive lens is moved farther away from the stop, in an attempt to correct the distortion.
The second lens is changed to an Aplanatic shape to minimise the aberration.
By looking at the lens, knowing what each lens does, we can clearly see Bertele's intentions, it's like we're reading his mind!
Another thing we notice is that the symmetry about the stop is not that high compared to a triplet, so the field of view is narrower. However, a lot of the aberrations were corrected and it was possible to make a lens with an F-number of F2 and F1.8, which at the time (remember, this is the 1920's) made for a lens with an extremely large aperture.
The Ernostar made large apertures possible and allowed for the birth of reparative photography pioneered by Erich Salomon, but the large asymmetry about the stop caused coma aberration. Therefore, the field of view for a normal lens, about 50mm focal length for 35mm format, was not possible, whilst this was perfect for portrait photography it had limitations for landscape photography. Also, without an anti-reflective coating technology at the time, the more glass-to-air surfaces there were, there was more flare, and the transmission and contrast of the image decreased. Most of the shortcomings of the Ernostar lens, however, were satisfied later by Bertele with his Sonnar design.
In every sense, the Ernostar was a lens ahead of its time. Even today, a lot of medium telephoto lenses share characteristics with the Ernostar.
I just mentioned the Sonnar design ale by Bertele so how did he come to design that for Zeiss? Ernemann was merged 1926 into ZEISS-IKON and Bertele found himself a lens designer in Jena. Already in 1924 he succeed in scaling down the Ernostar f/2 integrating a cemented group consisting of three elements (triplet). At Zeiss he managed to connect the third and fourth element, and therefore reduced the total of optical groups to three and effetively reduced objectionable reflections and stray light. Within a year he afford to enhance the aperture of that lens about virtually one f/stop to f/1.5 by means of replacing the last element with a cemented group of two.
Well I have over 200 vintage lenses, fortunately most collected before the mirrorless revolution, many listed here and many of them are now very collectable. Before now I would have said my favourites were the Canon Dream Lens for its Bokeh, Carl Zeiss f0.7 for its light flare and a pre war Contax Carl Zeiss 50 1,5 which I normally keep on my camera for normal stuff.
But when this piece of history appeared as a buy it now on eBay already converted to 42mm and for well under half the price of a modern lens I just had to buy it quickly before anyone else did. As stated above Bertele for me as a lens collector was just a genius and if anyone here has not read up about him above, about Heinrich Ernemann and what Dr. Erich Solomon did with this lens to change photography forever, you should do so now.
When you even start to like to sniff your fingers to smell the 100 year old grease you get on them because of the external helicoid you know you must be hooked! And you will get grease on them as the adjustment for the aperture is at the end of the extended helicoid. Even stopped down the Bokeh is just amazing, I could control the depth and pop at ease.