Designing a pancake lens for the M-mount is an exercise in physics and compromise. The market is flooded with diminutive optics that prioritize form factor over image fidelity, often relegating them to the status of 'toy lenses.'

The Brightin Star 28mm f/2.8 attempts to challenge this paradigm. It promises the build quality of a boutique optic and the performance of a serious tool, all within a housing barely larger than a body cap.

In this comprehensive review, we analyze the unique 'progressive' distortion, the realities of its unit-focusing design, and the specific optical constraints one must accept to gain such portability.