Video narration
Have you ever looked through a microscope and seen almost nothing, even though the specimen is there? A clear, unstained microorganism can let light pass through, so in bright-field microscopy it blends into the bright background. Magnification makes it larger, but doesn't automatically make its edges stand out. Think of dust in sunlight: tiny particles are easier to notice because they scatter light. A microscope uses scattered light differently. That's dark-field microscopy: a way of illuminating a specimen so direct light stays out of the objective, while light scattered by the specimen enters and forms the image. The specimen doesn't need to become opaque. It isn't glowing; scattered light is what makes it visible. Put the views side by side: in bright-field, the clear specimen nearly disappears; in dark-field, the same kind of specimen stands out against darkness. Tiny, transparent, unstained specimens become easier to see.