Last week someone mentioned the BW Polaroid film that was used for view-camera exposure testing, but allowed you to preserve the Polaroid prinnt and even its negative. It yielded quite lovely tonal transitions – often better than the actual film exposure. Perhaps you can still see this in a scan of a 4x5 polaroid print:http://www.flickr.com/photos/thompsonkirk/6212011748/in/photostream (To Don Williams: The little print was scanned on the flatbed part of a Canon 9000F, and then enlarged. I still use it for that.) Kirk