Hello!

I have Ursa Mini 4.6k and recently bought a secondhand SLR Magic Anamorphot 2x. However, I cannot find definite information on what lenses would be compatible and work with it. I have some primes (Canon 50mm and Helios 58mm) but both have a moving front element.
Do you know which lenses would work?
I was looking at Sigma Art 50mm, but from what I can tell, the front element is 10mm bigger than the real element of the Anamorphot?

Thank you, help would be incredibly appreciated!