Dear Friends, I have a very good Carl Zeiss Jena MC Flectogon 20mm 2.8 lens in very good condition. The aperture blades seem to be stuck wide open. The starry sky picture made with this lens looked like a bunch of doughnuts wide open. I am trying to solve two issues here: better focusing at infinity (obviously) and also would be glad to find experts in the UK, preferably not far from Oxford who could have this lens repaired on a budget. Aperture blades seems to be the only issue here. I am connecting it to my Nikon D500 via an adapter that has a glass element (for obvious reasons) and definitely would need to try this lens on a mirrorless camera. Would be grateful for all your thoughts on aperture blades repair and the infinity focus. Thank you.