In the case of objectives that do not have a correctioncollar, attention should therefore be paid toobserving the recommended cover glass thicknessand adjusting the refractive index of the mountingmedium to the refractive index of the objectiveimmersion. Otherwise, the result is an image withpoor contrast and bad resolution.In the case of objectives that do have a correction collarit is possible to compensate for deviating valuesin the cover glass thickness and differences in therefractive indices of the objective immersion andmounting medium. In addition, the increasing sphericalaberration that occurs when imaging deep-lyingstructures in thick samples can also be corrected.