Olympus 9mm f/8 Fisheye Body Cap Review

The Olympus 9mm f/8 Fisheye Body Cap is a specialty ultra-compact lens designed to live on your Micro Four Thirds camera when you're not shooting. At just 30 grams and half an inch thin, it functions as both a protective cap and a fun creative tool, offering an 18mm equivalent focal length with a dramatic 140-degree fisheye field of view. With a fixed f/8 aperture and manual focus operation limited to two positions (deep focus and close-up), it's built for spontaneous wide-angle shots and experimental compositions rather than critical optical work.

The lens uses a simple 5-element design with two aspherical elements and minimal glass, which keeps it featherlight but also limits its versatility. There's no autofocus, no aperture control, and no filter thread. The 1:20 macro ratio and 20cm minimum focus distance let you get reasonably close for such an extreme wide angle, but image quality and usability will naturally take a back seat to portability and novelty. At $125, it occupies a niche space for Micro Four Thirds shooters who want a pocketable fisheye that doubles as functional protection.