The first mirrorless digital camera was the Epson R-D1, which was introduced in 2004. The truth is, mirrorless cameras can be traced back to 1916, with the introduction of the Kodak 3A Autographic Special, a rangefinder film camera—or even further back still if we want to factor view cameras and plate cameras into the equation. Despite this, in the contemporary sense, mirrorless digital cameras are still relatively new, but there’s no doubt they’re also incredibly popular. Camera manufacturers have shifted their R&D budgets away from DSLRs and are focusing instead on the mirrorless market, where imaging technologies, including lens design, continue to evolve at a remarkable pace.
Mirrorless Camera Systems: They’re Smaller, Lighter, and Faster
The major benefits of lenses designed specifically for mirrorless cameras, including rangefinder cameras, compared to their DSLR counterparts have to do with size, weight, and, depending on the lens, speed. By doing away with the camera’s reflex viewing system, that is, the prism, the mirror, and all of the parts that make the mirror flip up and down, lens engineers have been able to reduce the size and weight of mirrorless camera bodies and lenses greatly. Eliminating the mirror assembly also reduces focal flange distances, which is the key to smaller lens design.
Flange Focal Distances and Why They Matter
Flange focal distance, otherwise known as “flange distance,” “flange-to-film distance,” “flange back distance,” or—in its simplest form—“FFD,” is the distance between the rear of the camera’s lens mount and the sensor plane. This is the distance required for the lens to focus from its closest focusing point to infinity. Every camera system has its own flange distance, and it’s the size of the flange distances that determine which lenses can be adapted to which cameras. We dive more into this subject in our Introduction to Lens Mounts and Lens Adapters article.