Bronica 50mm lens focus problem

[FishyFish]

I noticed today that my 50mm Zenzanon lens focuses past infinity. The focus ring stops at the infinity symbol, but distant obects become sharp a little before that position is reached before slipping back out of focus again. I've shot a couple of rolls using the lens and can't say I've noticed any issues - even on subjects pretty close to the camera - so it doesn't *feel* like it's not focussing correctly, but something it out of alignment somewhere or other. Many shots were at smaller apertures too, which might have disguised any shortcomings, especially on subjects further away.

My 75mm doesn't have this issue - distant objects become sharp when the focus ring is on the infinity symbol.

I guess I need to shoot some more shots, paying careful attention to focus distances and aperture settings, but any thoughts on the issue (or non-issue, given I only noticed it by accident, rather than because of OOF results) are welcome.

 

[excalibur2]

Quite a few 35mm lenses are affected (incuding mine) and can be adjusted and info on forums or the net on how to fix (although I can't be bothered), hopefully someone on the net knows how to solve.

 

[StephenM]

Probably a complete (infra) red herring, but IR focuses further back than visible light, so to focus IR at infinity requires focusing on a distance beyond infinity.