I have tried the tape measure idea using a 50mm Zuiko lens as loupe.
I also ensured the film was properly loaded and that the film holder was pushed in properly.
Exposure was at f5.6 and 1/50th sec.
I focussed on 15 inches which was about the middle of the tape.
Developed in Rodinal 1:50 for 15 mins.
15" was the sharpest area of the image and the image was also sharper than anything I have seen before. I reckon you have helped me to solve the problem.
Thanks very much.