Career
According to the RKD he didn"t move to Haarlem until 1757. He was the pupil of Frans Decker and Wigerus Vitringa. He painted landscapes, portraits, and copies of old masters.
His grisailles followed the manner of Jacob de Wit.
His pupils were Johan Bernard Brandhoff, Johannes Petrus van Horstok, Cornelis van Noorde, Martinus van der Jagt, and Johannes Swertner. He lived to a great age.
His pupil Cornelis van Noorde made many engravings after portraits that Jelgersma made. Often these are the only surviving portraits of these people today.