Viltrox 28mm f4.5 – An Autofocus Lens Cap

Lens caps that can shoot aren’t exactly new to the market, but they are certainly a niche, unique, and interesting product. If you’ve been using Fujifilm for a while, you might recall that they released the XM-FL before.

You can even make one yourself using a plastic lens from a disposable camera and a lens cap. While not many third-party manufacturers venture into this, 7Artisans and FunLeader are among those who create manual lens caps that shoot. These lenses are fun to use with no high expectations for image quality, typically featuring a slow aperture.

Then Viltrox shook things up by introducing something entirely different—a lens cap with autofocus. A concept so unique, no one else had even thought to try it.

Intro

The Viltrox 28mm f4.5 for X-mount officially launched on January 20, 2025. If you recall, Viltrox initially introduced this lens cap concept through an Indiegogo campaign—but that version was exclusively for Sony E-mount. Thankfully (no surprise), the campaign was a success, which eventually led to the release of the X-mount version.

Before diving deeper, I want to express my gratitude to the awesome team at Viltrox for sending this lens cap over. That said, my thoughts and experiences shared in this post remain completely unbiased.

Design and Build Quality

Weighing in at just 60 grams, this is the lightest autofocus lens I’ve ever used. Despite its featherweight, the lens features a full metal build—nothing about it feels flimsy or cheaply made.

Like most lens cap-style lenses, it offers only a single aperture setting. In this case, it’s fixed at f4.5 and there is no adjusting it beyond that.

If you prefer manual focus, the lens does include a tiny focus ring, giving you a bit of control when needed.

Image Quality

Image quality is fairly decent and nothing groundbreaking, but it delivers acceptable contrast and sharpness that’s more than enough for casual or social media use.

At f4.5, vignetting is definitely noticeable, though thankfully, chromatic aberration remains minimal and isn’t too distracting.

Given the fixed aperture of f4.5, background and subject separation isn’t as pronounced compared to faster lenses. That said, with the right composition, you can still achieve a pleasing bit of background blur.

Focusing

To my surprise, the autofocus performance is better than I have expected. There are occasional hiccups where it doesn’t lock focus on the first try, but it usually kicks in by the second or third attempt.

When it does work, the focusing speed is reasonable. Transitions between the minimum focus distance and infinity are decent—not lightning-fast, but perfectly acceptable for a lens of this kind. All of this is driven by a Voice Coil Motor (VCM), which gets the job done for a compact, chip-style lens.

Minimum Focus Distance (MFD)

No lens is without its flaws, and this one is no exception. It features a minimum focus distance (MFD) of 34cm—which, considering its compact size, is actually better than expected. Fortunately, image quality doesn’t take a hit at this distance. However, the depth of field remains fairly shallow and not particularly impressive.

Price Point

At just 99 USD, this is likely the most affordable autofocus lens you can get your hands on. With no direct competitors in its category and price range, it really stands out. Honestly, it’s a no-brainer for any photographer looking for a lens cap they can actually shoot with—practical, fun, and ready to go.

Others

This lens doesn’t come with a separate external lens cap—instead, it has one built in. A sliding lever lets you open it up for shooting or close it to protect the glass. It’s a pretty clever design. But the real question is: would you want to see this kind of innovation carried over to future lenses?

Like other Viltrox autofocus lenses, this one also features a USB-C port at the rear. It’s there for potential firmware updates. You might wonder what kind of updates a tiny “chip-sized” lens would even need—possibly improvements to autofocus performance or compatibility tweaks for newer camera bodies. Either way, it’s a handy feature to have.

Who is this for?

Everyone. Honestly, this lens is so affordable that I can’t help but recommend it to everyone, just for the fun of it. It’s the kind of gear that’s easy to enjoy without overthinking. In fact, it even makes for a great gift that won’t hurt your wallet.

Conclusion

This lens isn’t perfect by any means. The lack of adjustable aperture values can limit your shooting options and flexibility. However, I find it enjoyable to explore and shoot with this 42mm (full-frame equivalent) focal length.

While the fixed aperture is small, I do wish Viltrox could have made it a bit brighter—maybe around f3.5. That said, I also understand that a brighter aperture would require a larger, heavier design, which could defeat the purpose of creating a compact, lens cap-style shooter.

Overall, this is a fun and unique lens to experiment with. I’m looking forward to seeing more creative lenses from Viltrox for the APS-C and Fujifilm community.

Thank you for reading. 

Disclaimer:
1. All the shots taken here are shot by me.
2. Most of the shots are straight out of the camera with some shots edited via In-Camera Raw Processing.
3. The opinions are based on my experience. If there is any mistake, please kindly drop me a message and I will gladly make the amendment.
4. I reserve ownership of these images, if you wish to use my images, please notify me.
5. If you are interested in this lens and also wish to support me, this is the affilinate link to purchase

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