Hi Keith, I too have a Yashica but have never managed to track down anywheer that could/would order me any B&W filters

I got a (square) Lens Hood and 1A Filter at the same time as I purchased the camera

I have always had to hold a filter to the front face of the lower lens - not ideal but the only way I could manage.

If you uncover a source of filters please let me know

Martin