Fach-Prism Parallel 6 - 49mm Filter

Prisma filters are rotating prism filters that duplicate a part of your image depending on your model (parallel, prism...).

You can find out the filter thread size of your lens by measuring the internal thread. It does not correspond to the focal length at all: for example, a 50mm 1.8 lens can have a 49, 52 or 55mm thread...