I read in an earlier post regarding checking lens alignment that one of the SWC/M focus screen adapters also work on 500 series cameras. I have a question regarding that. I have seen a few of these adapters on Ebay, but wanted to know if my 500 C/m WLF would fit onto the adaptor screen? It looks like it might being that some of the adapters have what looks like identical fittings as on the top of a 500c/m body to fit one, but just wanted to confirm. IF not, do I need specific viewfinder parts for this? I like the idea of being able to check critical focus through the lens without having to use the WLF, or purchase a lot more expensive finder. Any thoughts?