Answer Happy

Always start out by focusing using the lowest objective and the least light needed and then moving to a higher objective. Once an objective have been focused, you can rotate to another one and the image will remain in coarse focus. The term describing this feature is The center of the field of view remains about the same for each objective. This means that objective is also As you use higher magnification lenses, the distance from the lens to the slide Be careful to use the fine knob to make adjustments and avoid bumping the lens with the slide.