Iselin is also developing a growing presence in the field of opera. A regular guest at Opera Hedeland, Denmark’s largest outdoor opera venue, he has conducted Le nozze di Figaro, La Cenerentola, Carmen and Rigoletto. In 2025, he conducted performances of Die Zauberflöte at Stockholm’s Folkoperan. He has been second conductor and assistant on productions including Smetana’s The Bartered Bride at Stadttheater Bern and Zimmermann’s Die Soldaten at Oper Köln, Elbphilharmonie Hamburg and Philharmonie de Paris.

Iselin has served as Conductor in Residence of Iceland Symphony Orchestra, and Assistant Conductor of Aarhus Symphony Orchestra. He won First Prize at the eighth International Jorma Panula Conducting Competition in 2021 (where he also received the Orchestra Prize) and received Second Prize at the German Conducting Award in 2023.

Iselin studied orchestral conducting at Sibelius Academy in Helsinki, Conservatoire National Supérieur de Musique de Paris, Zürich University of the Arts and Royal Danish Academy of Music and has been a Conducting Fellow at Verbier Festival. He has worked as assistant conductor to Michael Tilson Thomas, Sir Antonio Pappano, Susanna Mälkki and Vasily Petrenko. He counts among his mentors Mariss Jansons, Fabio Luisi and Sakari Oramo.

Alongside his conducting studies, Iselin completed degrees in percussion and harmony at Conservatoire de Paris. As a percussionist, he has performed under conductors including David Zinman, Dennis Russell Davies and Matthias Pintscher.