9 1/2 inch gold dot dagor filter size

[William Blunt]

I have a 9 1/2 gold dot dagor in an ilex no. 3 shutter and would like to know the front filter size. I think it's45mm but not sure. Thanks in advance.
Wm Blunt

[Bill_1856]

Most older lenses seem to have been designed for slip-on series filter holders, not today's screw-in filters. Just measure the outside diameter of the lens element, and start going through all those boxes of old series stuff at used camera shows, until you get one that fits.