Difference between Series VIII adapter and filter holder?

I have an Ilex 8.5" f/4.8 Caltar Series S lens which does not have any filter threads. The outer diameter of the front element is 62mm so I think that it takes Series VIII filters. I've been referred to an ebay seller who carries a lot of filter stuff and he has a 63.5mm push on adapter which he says can be adjusted to fit, and a filter holder as well. What is the difference? I don't need an adapter to another size, so I would have though that a push-on adapter would just have threading for the filters. Could someone please describe to me how these things work? I'm used to the newfangled stuff that just screws in to the front of the lens!

- Justin

Adapter is threaded internally at the front. Unthreaded filter drops in, is retained by a retaining ring (naturally) that screws into the front of the adapter. Entire assembly slips on to the front of the lens.

Thanks Dan, so the adapter is what slips on to the lens and the filter holder is actually a retaining ring that holds the lens in the adapter, sort of like the 2 piece mason jar lids?

Justin asked a question that I've been meaning to ask for some time (thanks Justin!). Now I have another related question.

I see some references to Series filters having thread sizes???

As the threads on the adapters are internal, are the thread sizes for the retaining rings such that one can screw commonly available metric threaded filters directly into the adapters, where the retaining ring would otherwise go, or are there also non-metric threaded Series filters that can be screwed directly into the adapter, where the retaining ring would otherwise go?

All of my questions arise because of the two lenses (90mm and 58mm) I have for my Koni-Omega. If anyone has some filter solutions for same, I'd like to talk .

TIA

Matt

mattking,
I've only got Series 7 & 8 to play with here
Series 8 actual diameter=63.5mm retaining ring is 67mm
Series 7 actual diameter =51mm retaining ring is 54mm
looks like there's a 3mm difference between the filter size & retaining ring.
Back in the days of yore you could walk into the local camera emporium & pick up a slip-on or threaded series adapter. No more.

You should be able to measure i.d. or o.d. pretty easily if you have access to a caliper. Local machine shop, school maybe even a local mechanic.
When you measure the i.d. the thread depth will give you about 1mm smaller than the actual thread diameter.

So if it measures 51mm it's a 52mm and you would need a 52 to Series ?
For a slip-on it's the actual measured diameter, so it's 54mm to Series ?

If you want to use one set of filters on your setup Series 8 should fit both but will be really big for the 90.

Justin,
The 63.5 slip-on is most likely correct for your situation. The tabs on the slip-on adapters are made to bend slightly. The Series 8 ring will take 67mm filters directly, no adapter needed. If you want to use the Series 8 filter you will need a retaining ring since Series filters are not threaded. 67mm filters are a lot easier to find than Series.

Thanks John.

Matt