Embarrassingly basic but.... Just wondering. The safe filter that you have below your lens on your enlarger, is that the same kind of thing as, say a Hoya #25 red filter...? I do have a (optically broken) #25 filter lying around and I kind of need a replacement for my existing safe filter on my enlarger (it's modified for medium format, so the safe filter doesn't cover the 35mm light totally, because that lens is further away from the filter itself). Can I use my #25 filter as a safe filter for my enlarger I wonder...? Can you buy this filter in sheets or parts somewhere? (what are the requirements for such a filter?).