It's important to keep an eye on the health and maturity of your precious crops, the only way to be sure is seeing the finer details up close.
Defining the maturity of your plants across the various stages of growth is a valuable resource in any experienced growers opinion, commonly using the microscope to identify the micro changes across the surface of leaves or fruits. However, this is also an equally important tool for diagnosing diseases or pests. Identifying potential plant health hazards before they take a hold may save you a lot of grief, sometimes a VERY close look is required with a microscope. You won't miss a thing with 60x-100x zoom.