Dust in a lens isn't a big problem. It really doesn't effect the image quality [1]. They had another tear-down to remove a fly from Canon 70-200mm [2], and it d

Dust in a lens isn't a big problem. It really doesn't effect the image quality [1]. They had another tear-down to remove a fly from Canon 70-200mm [2], and it didn't make difference until stopped down. 1: https://www.lensrentals.com/blog/2011/08/the-apocalypse-of-lens-dust/ https://www.lensrentals.com/blog/2011/08/the-apocalypse-of-l... 2: https://www.lensrentals.com/blog/2019/04/removing-fly-from-weather-sealed-canon-70-200mm/ https://www.lensrentals.com/blog/2019/04/removing-fly-from-w...