Thank you kindly for your comments and Gallerie link.
Although I usually do not accept advice from young bucks (I was born in 43, so I am older!!!!!!!!!!!!) I have to admit your link opened my eyes to new possibilities BUT, since you are definitely above my pay scale on this, let me run this for your, now-requested, advice.
I have a Scheneider III center filter in 67mm that I use with the 110mm f 5.6 aspheric XL Schneider and the Nikkor 65mm f 4.
Both of these are for the 4x5 format
In 8x10 I use the Aspheric XL 150mm f 5.6 and that one needs a 95mm filter for the front but, in your co authored article @ Chez Galerie, you list several rear element filters.
The 150 XL rear element holds a 62 mm filter easily, I thought it would not since the glass almost protur=des above the outer rim BUT I tried a 62mm front filter on its rear element and it worked just fine.
So, here is my question: Why not buy a 62-67 ring and use the 67 center filter I already own on the 150mm?
Will that work?
My guess is that it will not since the areas of "obscurity" will probably be augmented significantly by the rear placement.
This, if it will work, will save me a bunch and I could pay you (if you visit Paris or NYC often), with a great dinner with lots of good wine!!!!!!!!!!
Thanks again
Gaston
PS: Je ne suis pas francais mais je peux me esprese, dans la langue de Moliere, relativement bien.