Sorry for the late reply, I had to regulate a few things and couldn’t go on with my microscope.
I don’t want to remove the 50mm lens because it would be damaged as it sits very tight in the plastic holder.
I am using a different objective(60x from aliexpress, look for 32913301769) now and with the cover glass down I get it sharp and I am very happy with it. The objective says 60/0.65 160/0.17. I think 0.65 is the numerical aperture and 0.17(mm) the working distance.
@ImAreO I understand that the cover glass doesn’t fit with a 0.17mm working distance.
An idea: If I shorten or extend the objective holder is it possible to extend the working distance? Sorry for this noob question. I don’t know much about optics… clearly I’ll need a new 50mm lens in this case, too
When I am using fresh preparation of living material(like an oral mucosal cell) with the cover glass down it’s difficult to keep it in place…