Microscope Hemocytometer grid not visible

[diS]

Hi,
I recently bought a microscope Kern OBS 116 for yeast cell counting:
https://www.stoxxparts.com/en/transmitted-light-microscope-kern-obs-116-15002711001/
The problem is that hemocytometer grid is visible only on lowest (40x) magnification:

After changing objective to 100x magnification, grid can only be be visible as contours:

When using 400x magnification there is only white blurred image:

I tried to change condenser and diaphragm adjustment but without success.

Anyone got the idea why it is not working?

 

[hotbeer]

Does the microscope work for anything you've tried to view? Maybe the focusing knobs aren't changing the distance between the tray and lens when you spin them.

New microscope? I'd be checking with the people that can do something about it via return or warranty service. So either the seller or the maker.

 

[diS]

It shows fine image when using cover glasses without hemocytometer.
I tried to put sample on one glass and cover it with other and it is fine.

Could it be that hemocytometer thickness is the problem?

 

[passedpawn]

Seems like a focus problem. You've got plenty of light there, so I don't think the problem is anything below the stage (i.e., condenser/diaphram). With those high magnification lenses, you will need to have the lens almost touching the cover glass - that 40x will very close.

 

[diS]

Small cylinder at 40x objective is touching cover glass, so it pulls in when focusing.
Not sure is it fine to do that but even then I still can't focus.

Strange thing is that when using cover glass as base it focus pretty well, so my doubts are on hemocytometer thickness but probably I'm wrong as there were only 1 thickness available..