Ultra-thin Viltrox pancake prime for Fujifilm X, offering a quirky 42mm equivalent.
The Viltrox AF 28mm f/4.5 is an ultra-compact autofocus pancake prime launched in 2024, available in Fujifilm X, Sony E, and Nikon Z mounts. On APS-C bodies — the Fujifilm X and Nikon Z versions — it provides a 42mm equivalent field of view, sitting between the classic 35mm and 50mm perspectives. The Fujifilm X and Sony E versions measure 15.3mm in total thickness and weigh approximately 60g, placing them among the thinnest interchangeable lenses with autofocus available. The lens was designed for photographers and content creators who prioritise maximum portability and a discreet profile above all other performance attributes.
The optical design uses 6 elements in 6 groups, including two ED (Extra-low Dispersion) elements and two aspherical elements. The Fujifilm X and Sony E versions measure 15.3mm in thickness; the Nikon Z version is slightly larger at 16.8mm and 80g. Minimum focus distance is 0.34m for the Fujifilm X version. There is no filter thread — the front of the lens uses a fixed protective element design; external filters cannot be attached. Autofocus uses a stepping motor for smooth, near-silent operation. The f/4.5 maximum aperture is significantly slower than most pancake primes of comparable focal length. The Sony E version covers the full-frame image circle; the Fujifilm X and Nikon Z versions are APS-C format.
For street photography, travel, and casual daily use the 28mm f/4.5 excels where portability is the primary requirement. At 60g and 15.3mm thick, the Fujifilm X version makes a body-and-lens combination barely thicker than the camera body alone — practical for jacket-pocket carry with compact mirrorless bodies. Optical quality is strong in the centre at typical apertures. The slow maximum aperture means the lens is most effective in good light; low-light shooting requires raising ISO or accepting motion blur. The 42mm equivalent field of view is versatile for general shooting but offers neither the contextual width of a wide-angle nor the compression of a portrait prime.
The Viltrox AF 28mm f/4.5 is a niche product aimed at maximum compactness rather than all-round performance. On the used market it is relatively new with limited availability. The Fujifilm XF 27mm f/2.8 R WR offers significantly faster aperture with weather sealing and a similarly compact form at a higher price — the more versatile choice for most shooters. The Viltrox is the right choice when nothing in the autofocus category matches its thinness. Check autofocus responsiveness and the lens mount seating for any play or looseness. The absence of a filter thread is an absolute constraint — there is no workaround.