Those PRODAP adapters may be hard to find, as they were not a "Durst" product.
Two things I have done:
1) Look for lenses that already come with the adapter from Schneider/Durst.
2) Stock up on Vapla lensboards. These can easily be modified to accept nearly any lens.
These lenses came with the adapters in place from Durst/Schneider. Sometimes you have to buy extra lenses and swap out the glass elements or swap the adapter base to get a good working lens. Again, these are easier to find than the PRODAP adapters. In the case of the 240mm, I swapped all the lens cells from one barrel to the other to get the best glass in the best barrel.
The other thing that works well is to stock up on Vapla lensboards on e-bay. Most lenses with flanges can be mounted this way. Even if the hole is too big, you can always fashion some sort of adapter for a through-hole mounting with a ring.
That's a fairly uncommon board (vs the turret style). But it's not too hard to make your own if necessary, or have a local machinist do it. Just make sure it's truly stiff and rigid like the original.
This is the same Durst lens mount system as used on the Durst 138. With larger lenses, the threaded lens flange can be modified to fit by cutting down the OD to match the Durst lens mount then adding the chamfer length and angle matching the Durst OEM. Alternatively, the proper lens mount to fit the Durst can be made as needed on a lathe by a skilled machinist.
Flatness, accuracy and precision of the lens board and lens mounting is a must.
Bernice
Some lenses are simply too big for any of the standard turret rings, for example, a 360/5.6 El Nikkor.
this one has a 130mm thread, while the 138 turret lenboard type is around 77mm...Originally Posted by Drew Wiley
I love that big lens for its brightness at time of focus on color neg film, where the orange mask indeed masks a lot of detail as seen through a grain magnifier. But for 8x10 b&w negs, I prefer 305 and 360 Apo Nikkors, which fit in the turret rings and are actually optically superior to the El Nikkor, though most people would never notice the difference in a print. 138 and 184 turrets and rings are the same, interchangeable.
The original Vapla is cast, but I have seen machined replicas on the glennview site:
I'd worry about the dimensional stability of plastic. It would be easy enough to make something like this in any halfway decent shop, if one has the right tooling. Just another variety of lensboard. I adapted my biggest enlarger to accept Sinar boards, though even one of those is overwhelmed by a 360 El Nikkor. Speaking of which - gotta go load a new neg in my 138 in a moment. It's a bit windy and clear-cold for shooting outside today. Think the light will be softer tomorrow. Got particular subjects in mind, where I want some overcast.
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