I was thinking about using the microscope for a heavy workload and the inevitable build-up of rosin vapor on the lens and the loss of efficiency when having to clean a lens in the middle of a complex job. I'm wondering if there are clear no-magnification "lenses" that can screw-on in front of the existing lens. In that way with two clean 1x lenses when one becomes dirty it can be easily swapped out without moving the microscope. Depending on workload then both 1x lenses can be cleaned at once at the end of the day or the dirty one can immediately be placed in an ultrasonic cleaner and be ready to reuse sooner, but all without having to clean the main lens in the middle of a job.