Stereo Microscope Focusing

On occasion, we get a stereo microscope back from a customer with the complaint that it does not focus. Sometimes the microscope is defective, of course, but most of the time, not focusing is a matter of the customer not knowing how to adjust the microscope. Stereo microscopes are designed to be used with a huge variety of specimens from twigs, rocks, leaves, circuit boards, machine parts, and so on. These objects vary widely in size. In order to accommodate these different sizes, the head on most stereo microscopes, such as the excellent LOMO SF-100, is mounted on a vertical shaft which allows the microscope head to be moved up and down as needed to make room for the specimen. Quite simply, if, after placing the specimen under the microscope, the microscope fails to come into focus, the head needs to be moved up or down to come within the working distance of the optical system. Just loosen the locking knob on the head and raise or lower the head as needed. Not a big deal and, with experience, it becomes second nature.