B&W 52mm filter Stern 6X

[Dr David Hall]

Have found that over the years I have accumulated a lot of filters but this one I don't remember. It is a 52 mm,it is marked B&W Stern and 6X. it rotates like a polarizer but doesn't seem to polarize. Does anyone know what this does? Thanks

[Helen B]

A star filter? Stern is German for star.

Best,
Helen

[Dr David Hall]

Thanks Helen, I will put it on a Nikon and point it at a light source and see if it creates a star pattern. It is a curious thing....thanks again for the suggestion. David