A Tiny $99 Autofocus Lens: Is It Worth It?

The Viltrox AF 28mm f/4.5 XF lens is one of the most compact autofocus lenses you can get. It weighs next to nothing and turns your camera into something truly pocketable. But is it worth the $99 price tag? There are some trade-offs to consider, and some of them may be deal-breakers depending on how you shoot.

Coming to you from Dustin Abbott, this thorough video looks at the Viltrox AF 28mm f/4.5, a lens originally designed for full frame Sony cameras but now adapted for Fujifilm’s APS-C system. Due to the 1.5x crop factor, the focal length becomes a 42mm full-frame equivalent, which sits in an interesting middle ground between a classic 35mm and 50mm. There’s no aperture control here—the lens is fixed at f/4.5, meaning you have to work within its limits for depth of field and exposure. It also lacks manual focus, relying entirely on autofocus performance. Abbott points out that this makes autofocus accuracy critical, since there’s no backup if the system struggles.

The lens is built with portability in mind, measuring only 0.6 inches in length and weighing 2.1 ounces. It has a built-in front cover that slides open and shut, replacing the need for a traditional lens cap. While that design choice adds convenience, Abbott notes a potential vulnerability: when the camera powers on, the focus mechanism extends slightly beyond the cover’s sealing point. That could lead to dust or debris sneaking in over time. Optical performance is mostly unchanged from the Sony version, but Fujifilm users get a slightly different minimum focus distance—34 cm instead of 32 cm—which results in a small improvement in magnification.

Key Specs

• Focal Length: 28mm (42mm ful frame equivalent)
• Maximum Aperture: f/4.5 (fixed)
• Focus Type: Autofocus (no manual focus option)
• Minimum Focus Distance: 1.1 ft (34 cm)
• Image Stabilization: No
• Filter Thread: No
• Optical Design: 6 elements in 6 groups
• Dimensions: 2.4 x 0.6 in (60.3 x 15.25 mm)
• Weight: 2.1 oz (60 g)

Autofocus is one of the more interesting aspects of this lens. It uses a voice coil motor (VCM), which should theoretically provide smooth, silent focusing. However, Abbott observes that while the autofocus worked well on Sony cameras, it seems to introduce small stepping movements on Fujifilm bodies, likely due to how Fuji’s autofocus system interacts with the lens. It performs better in bright light, but in lower light, those micro-adjustments become more noticeable.

Image quality is a mixed bag. The lens’ contrast and sharpness vary depending on lighting conditions. If the light source is at an angle, contrast can drop, giving images a hazy, vintage look. When the light is more direct, results improve. The fixed f/4.5 aperture limits depth-of-field control, making subject separation harder to achieve unless the background is far away. While there’s some focus breathing in video use, Abbott notes that it’s not significantly worse than many other compact lenses. Check out the video above for the full rundown from Abbott.