The phrase "an unfamiliar medium" is correct and usable in written English.
You can use it when referring to a form of communication, art, or technology that is not well-known or commonly used by the speaker or audience.
Example: "As an artist, I decided to experiment with an unfamiliar medium, which challenged my creativity and skills."
Alternatives: "a new medium" or "an unknown medium".
But another is that most participants were trying their hand with an unfamiliar medium.
The first figures and scenes naturally show the artist reusing devices from his earlier works, such as the Pietà, since he was starting on such an ambitious work in an unfamiliar medium.
This has changed thanks to the development of a line of research, known as Experimental Semiotics, in which participants construct novel communication systems in the laboratory using an unfamiliar medium.
Forlow Justhoseaffier on Twhoter.
Lennox-Boyd argues that the illustrations in the edition have a "uniformity and cohesiveness" that the folio lacks because the artists and engravers working on them understood book illustration while those working on the folio were working in an unfamiliar medium.
We do not wish to doubly challenge students in both content and an unfamiliar medium for an assignment.
Faced with an unfamiliar live and musical medium, superb cinema directors can seem out of their depth: no close-ups, no fascinating camera-angles, and certainly no relying on the dramatic expertise of those in the leading roles, who are not generally selected for their acting.
And yet the malice was inventive; Deakin did nothing for war or fashion photography, but in his confrontations with the human face, brooding and unadorned, he forced the medium along an unfamiliar path.
At the end of all this, even though the only realistic reaction from the chicks and rabbits would be one of blank animalistic indifference to the onslaught of images, sounds and ideas that they cannot possibly comprehend presented in an alien medium in an unfamiliar location, the creatures somehow managed to score the trailers.
This is an unfamiliar feeling.
Then came an unfamiliar sound.
