[Millsy (Andrew)]

Ok so I bought an L-Extreme duo band filter secondhand.
To be honest I expected more. It was ok but I dont see much difference than I did with my Zwo Duo Band.

I was expecting the earth to move and wow to come next but it didn't happen. Now all this has left me with that feeling of, did I get duped ??

It looks easy enough to do, screw out the retainer ring and pop in inferior glass but how do you know ??

Is there a way to test my little shiny circle of mirrored glass or is there some teltail marking I can see that will at least put my mind to rest ??