This Steinheil Quarzobjektiv f1.8 / 5cm (50mm) is from the Steinheil Museum and I was very lucky to be able to be there at the right time when parts were dissolved. Only one lens is known, this one.
So today I was digging for some stuff in that lens fault, when the really nice weather made me want to give it a ride to the park for the last hour open. So here some results, quite open and quite closed aperture for comparison:
[click on image to see a larger one]
Even dating from the 20ies of this century, it performs quite well, especially at that enormous speed of f1.8 - which was needed, as it was made to record faint spectra of Steinheil's famous "Quarz Spektrograph". It is most likely a 4e4g lens design, so astonishingly not a triplet.
I was able to record some "UV yellow" flowers reflecting around 360nm, which funny enough are also deep yellow in visible light.
Stay tuned, more will follow on that fascinating subject...
More info on this very interesting field may be found on my site http://www.pbase.com/kds315/uv_photos