Aquired a Laborlux dual head microscope. The lower powers, 2.5, 4, 10 work very well however the 40 is only sharp on the right edge, never elsewhere. It also lacks contrast. Physical examination of the objective shows no damage to either end. The lower end is sprung and works fine. Is the objective damaged or some other explanation?
Hello @Akademic and welcome to the forum.
It is hard to know for sure without examining the objective but sometimes, e.g. if an objective has been dropped, one of the lenses may have dislodged from its mounting to be a bit slanty instead of flat on. The lens itself may not look damaged but the wrong siting position can cause lack of planarity.
However, in that case focussing up and down can shift the ‘sharp’ region from one side of the field to the other. In your case it seems the ‘sharp’ regions is in a fixed position regardless of focus position (is that right?). In that case it may be that something (a bit of immersion oil inappropriately applied at some point in the past perhaps) has gotten into the lens casing and is causing a fixed area of blurriness.
Those are some possibilities. Without a detailed examination of the lens it is not possible to know for sure what is happening in your case.
PJT
Thanks for the feedback. I would expect an oil leak to be right across given the very small volume between lens elements.
I doubt it is worth trying to service the lens.