I've discovered that a lens I have takes series 8 filters. Since these are hard to come by I've been trying to find a push-on adapter that has threads to accept the current standard metric screw-in filters. B&H has adapters going from metric to series, which is the opposite of what I'm looking for. My lens does not have threads so the adapter needs to be push-on type. Does anyone know where I can find one of these?