I have the Rolleisoft 0 and 1 filters for both bayonet 1 and 2, and the earlier Duto-filters for the Rolleiflex Standard. They are all of the Duto-type with concentric rings that superimposes a weak unfocused image onto the focused image, creating a nice softening effect. The effect is depending on the aperture, and it's not recommended to stop down more than max f:8.


I haven't used them much. but here's an example taken with the Rolleisoft 0:


http://farm9.staticflickr.com/8265/8...f6b555b4_b.jpg

Close up:


http://farm9.staticflickr.com/8257/8...52effc03_z.jpg

A portrait taken with a 1938 Rolleiflex Automat, Aperture f:4, Light green filter and Duto 1.


http://farm9.staticflickr.com/8546/8...dfa3ee11_z.jpg