Ryuji, all my 4x5 lenses are either Schneider or Rodenstock. I don't know if you call them decent, but I haven't found any information on IR focusing in their data sheets. If you've got something, tell me about it.(posted 8208 days ago)Howard, yes, but the hyperfocal distance for IR will not be the same as the one for visible light. I've got the formulas to calculate the normal one, but how about the IR one ? Well, I am sure all this is too much fuss about focusing precision that might sound too perfectionistic for many people, but there are lads that worry whether their 4x5 sheets stay flat in their chassis when shooting, aren't there ?