The master who painted the picture The Last Supper on the Vigala retable’s central panel wrote his initials H. S. in its corner. Researchers have not succeeded in identifying the master behind the signature.

The painter’s signature in the corner of The Last Supper is more of an exception instead of a rule – Ackermann did not leave his signature on any of his works. Even Ernst Wilhelm Londicer, who returned to Tallinn in 1683 and established himself as an independent master, is known to have signed only one of his works: in 1678 on his portrait of Gerhardt Lode.

The painting The Crucifixion of Christ on the retable’s additional storey is unsigned. The picture’s format is smaller, and its composition is more complex than The Last Supper. It was painted using finer paintbrushes and even brighter colours.