Etienne Decroux- around 1975 – in his studio in Billancourt (suburb Paris, France)
PHOTO CREDITS MANDATORY:
Photo © Christian Mattis Schmocker, Bern Switzerland. www.mattis.ch
Please do not crop the photos!
“I studied with Etienne Decroux from 1974 until 1977. I was the only person allowed to take photos from time to time – during class, but also during M. Decroux’s lectures Friday evening; and during the work with Denise Boulanger and Jean Asselin on the three «Duos Amoureux» and filming of them.
I used an analog SLR (digital didn’t exist at that time) with a film roll of 36 images. The film material was Ilford HP5 or Kodak Recording. I enlarged the photos in the darkroom myself.
In 2018 I scanned the original negatives and cleaned the photos from dust and scratches in Photoshop.”  CM

More on Etienne Decroux on Wikipedia. Note that the different Wikipedia sites (deutsch, english, français etc) all have adifferent approach to E.D.
Deutsch LINK    English  LINK    Français LINK