[2] Between 1587 and 1588, Widemann worked in Prague for Edward Kelley at the court of Emperor Rudolph II.
He did the same for the works of Caspar Schwenckfeld, and Widemann's close colleagues Valentin Krautwald and Adam Reissner.
After Helisaeus Roeslin's (Helisäus Röslin) death in 1616, his unpublished astrology, theology and kabbalistic work merged into the manuscript collection of Karl Widemann.
Adam Haslmayr a close friend of Widemann, wrote him a letter about Rosicrucian people who revealed the Theophrastiam, on December 24, 1611.
[2] In March 1599 Emperor Rudolph II bought several "remarkable/rare books" from Carl Widemann for 500 Taler.