I have a really basic question. I own quite a few B+W filters, and would like to know if it is possible to use GND filters (100mm lee or singh ray filters in lee or Cokin P holders) in conjunction with my threaded, circular B+W filters. For example, if I want to take a photo with an 81-series B+W filter AND a GND filter, is there a way that this is possible without degrading the image quality? If so, what accessories would I need to make this possible?
Thanks for your help.