Photonic impaction, the problem with lenses created by the accumulation over time of stray photons, afflicts lens instruments other than cameras. While the problem is well-known among astronomers (related, perhaps, to the still-hypothetical photon belt), it does not occur ― save in rare cases ― in the field of microscopy. Simply put, lenses pointed up appear prone to impaction, while lenses pointed down generally do not. […]