jomocovi

I have suffered exactly the same problem with my Macro Elmarit 60mm on a Sony A7ii as you did with your 5D and found it was caused by an internal reflection in the lens barrel parts when extended for macro zone in combination with aperture blades oil glare. I decided to send it to a repair house as soon as I found the phenomenon present in film with my Leica R 6. By cleaning the blades and painting all the possible internal parts of the barrel in matte black, the problem has gone. (I was not able to detect which of the two was more relevant for the white spot problem).