What would be the longest focal length lens I could use and focus down to 20ft or so.?
I have been using my 210mm G-Claron at this distance.
I know the back cell of my Beck Biplanat has a focus of 10.5" or 266mm.
That won't focus down close enough.

I just bought a lens by Auzoux of Paris. The thing is a real cannon, what a shame. I can't focus that, even at infinity. I think this is of around 290 - 300mm.

The longest standard issue lens for the 4x5 Crown was the 15"/5.6 TeleOptar, also sold by Wollensak as a TeleRaptar. There are, I think, similar lenses from Rodenstock (Rotelar) and Schneider (Tele-Arton, Tele-Xenar) that will also do for you.

What Dan said.
The 15" Tele-Optar or Raptar (380mm) will pull you in pretty close. Not bad image quality either, and reasonably fast at f5.6. One of the better Wollensak Tele lenses, and mine isn't in the best condition. Will make better than 20ft no problem. The issue I found with it is the weight out in front of the camera base support. And mine is in barrel on a Speed. A Crown would require the front shutter adding more weight.
I made an aluminum plate to place the support center under the camera with holes drilled and threaded etc to mount the camera body at the backof the plate with a thumb screw and the tripod head threadedinto the center of the long plate. Way better. The Graphic is a reasonably firm camera and the front standard very stable with lighter weight lens shutter combos like the 203 Ektar, but not so good with four pounds of glass and hardware way out in front.

Primus, did you try the Auzoux on your camera, or are you assuming that you cannot get it to infinity? Even though it evidently does not have "tele"in its name, it may be a true tele and require a relatively short bellows draw. You do not have to mount the lens to check it out, just hold it in front of the front standard and get an idea as to where it would be to reach infinity.

If it is in need of only one or two inches of bellows draw beyond what the camera can provide, you could make a riser lens board to gain the extra distance. If the lens is a real cannon the load on the front standard is a consideration, especially with a deep riser lens board. I have the Tele Optar/Raptar that Dan and Troublemaker mentioned (both barrel and in shutter) and they are a load on the front of the camera, but manageable.

You did not say what the FL and aperture of the Auzoux is; is the lens not marked?

John

With the front standard flush with the end of the rails and the rails run fully foward, what is the distance from the lens board to the ground glass on your camera? It should be 12 1/2 inches. If the bellows length is correct then fabricate a lens board extension of 1 inch or so to put the lens futher foward allowing for closer focusing.

The lens will not focus to infinity and I don't wish to strain the bellows of my Pacemaker Crown Graphic. Focus down to 20-30 ft is essential, so i'd need yet more bellows extension.
This lens has a flange - focal plane measurement of around 300mm. Speed-wise I would say f8-11. I do not have the original Waterhouse stops.

Will this fit a Graphic View?

Graphic View: 12" bellows
Graphic View II: 16" bellows

It's not me that has a Graphic View.
The lens is not likely to be of any use to me, so someone else might be able to use it.