Actina Thread size???

I have an ancient Actina Polariser which uses an Actina Step ring to adapt it for my 49mm filter ring on my 50mm A lens.
I want to fit the polariser to my 52mm DA lens and I want an appropriate step ring (right name?). The o.d. of the filter ring seems to be about 59mm but is it likely to be a thread compatible with the standard lens filter thread?
Has anyone any ideas about this? The filter is in good nick (and it doesn't seem to interfere with focussing, either!) so a bit of internet shopping could produce the right adapter IF my estimate of thread measurement is right. I don't really want to use chewing gum each time I use the polariser on my k10. It tends to lose its flavour overnight. (Obscure reference- I wonder how many younger readers get it)

My best guess is that the threads would be compatible, but I would be surprised if you can step down from 59mm to 52mm in just one step ring.

The Actina adaptor goes direct, but I suppose it would!
I don't care doing it in more than one step as long as I can be sure I'm buying something that will do the trick. I can't be too sure that it is 59mm. I do miss the ever-helpful camera shop, these days. Jessops is the only local one and they know naff all about anything.

Look for SRB on the web - they make every kind of adapter you could wish for and they may well know the thread size of your filter.

Your Polariser will almost certainly be a 58mm thread size as 59mm would be a non-standard size (measure the outside of the thread, not the filter itself). SRB do 52-58mm step rings for £4.90

...but John has quicker fingers

Thanx all!
What a goldmine of info, this site is.