Understanding Filter Turret Registration Problems
Microscope manufacturers all use removable filter cubes in turrets or sliders on their epi illuminated microscopes. When a filter cube is inserted into an individual turret location, the tolerances associated with that fit can often result in a shift in the orientation of the field diaphragm. As seen below, where a filter is inserted into different turret positions, the tolerances associated with a filter cube positioning will result in a shift in the orientation of the field diaphragm. The same effect can also happen when reinserting the same cube in the same turret position. This makes the process of multi label imaging with different filter cubes frustrating while trying to minimize sample exposure by using a field diaphragm.
The images below shows how a filter turret tolerances show up not only as field diaphragm shifts when they are combined, but also create colocalization problems between fluorophores.