| No light from light source |
Power switch off |
| Power cord improperly connected or not plugged in |
| Problem with power supply |
| Blown fuse |
| Faulty bulb/defective bulb contacts |
| No light seen through microscope objectives |
Light source covered |
| Field diaphragm closed |
| Aperture/iris/condenser diaphragm closed |
| Objective not in the light path |
| Field only partially illuminated |
Condenser off-center |
| Aperture/iris/condenser diaphragm closed too much for the objective being used |
| Field diaphragm partially closed |
| Objective only partly in light path |
| Electrical cord lying in the field |
| For Nikon 50i: neutral density filter partly pushed in |
| For Nikon 50i: optical path switching lever (for camera) in incorrect position |
| Weak illumination |
Light adjustment knob/rheostat/lamp voltage turned too low |
| Light source covered or burning out |
| Aperture/iris/condenser diaphragm closed too much for the objective being used |
| Condenser too low or not centered |
| Using oil immersion lens with no oil |
| For Nikon 50i: neutral density filter engaged |
| For Nikon 50i: preset switch has been engaged (only required for camera use) |
| Uneven illumination |
Light source not centered |
| Condenser not centered |
| Field of view too bright |
Light adjustment knob set too high |
| Image cannot be focused |
Slide very dirty/greasy |
| Slide up-side down |
| All objectives dirty |
| Dirty eyepieces |
| Diopter adjustment improperly set |
| Vibration on the bench |
| Image very yellow |
Blue filter missing |
| Light adjustment knob set too low |
