A reflex lens, also known as a mirror lens, is a type of photographic lens that uses mirrors instead of traditional lens elements to focus light. This design allows for a more compact, lightweight lens, particularly useful for capturing telephoto images without the bulk of conventional long lenses.
Reflex lenses are often favoured for wildlife, sports, and astrophotography where extended reach is required. While they can produce unique optical characteristics such as donut-shaped bokeh, they offer a practical solution for photographers needing high focal lengths in a portable form.