Joe and Grant, thank for your comments!
About the shutter for this barrel lens: I use a Sinar behind the lens shutter - a very old one belonging, I think, to Sinars Norma camera, but a well working Copal shutter without aperture control, the fastest speed 1/60" (can also use it with other barrel lenses such as my Apo-Nikkor f9/360mm and f9/480 -- these barrel lenses are quite cheap on eBay but has enormous image area (image area for the 760 mm lens is 1170 mm!!) and often called "process lens" - probably optimized for reproduction work but works reasonable good for other things also.)
//Bertil
Many thanks Ignatiu5 for your nice comment! (and johonnywalker too, though it was a long time ago, didn't see your positive comment until now!)
/Bertil