why is it important to start with the scanning objective in place, rather than the high-power objective?

It is important to start with the scanning objective (low magnification, typically 2x to 4x) rather than the high-power objective in microscopy because the scanning objective provides a wide field of view that allows for easy location and overview of the specimen. This makes it simpler to find the area of interest on the slide before switching to higher magnification objectives for detailed examination. Starting with a high-power objective would limit the field of view, making it difficult and time-consuming to locate the desired part of the specimen. Additionally, the scanning objective's larger working distance reduces the risk of damaging the slide or objective lens while focusing initially. Most microscopes are designed so that once the specimen is in focus under the scanning objective, it remains roughly in focus when switching to higher magnifications, making the process efficient and user- friendly.