After making headlines for producing one of the slimmest full frame mirrorless autofocus lenses last year, Viltrox has made a bold move by making it available for the Fujifilm X-mount as well to fill a market gap. Introducing the Viltrox 28mm f/4.5 Fujifilm X-Mount, also known as a “chip” lens, resembling a potato chip—a reference to how thin the lens is. This Chinese lens maker even carries on the humor by featuring a bag of chips in the lens announcement poster, which was published on their Chinese social media.
Being one of the smallest APS-C autofocus lenses on the market, the Viltrox AF 28mm f/4.5 weighs only 60 g with a 15.3 mm thickness—almost as thick as a lens cap. Its compact size allows smaller cameras, such as the Fujifilm X-M5, to be pocketable and lightweight when attached. Honestly, I was pretty surprised by how slim and light the lens profile was when I first received it, especially knowing that it was designed as a full frame lens first and then converted into an APS-C mount for Fujifilm.
Keeping the same optical formula as their full frame lens, we can be assured that this lens is going to deliver strong performance on Fujifilm’s APS-C mirrorless cameras. This is because, on an APS-C camera, only the central portion of the image circle will be used, resulting in better image quality and reduced vignetting compared to its performance on a full frame camera.
One thing to note is that when using this lens on an APS-C camera, the effective focal length will be 42mm with a 52.07° angle of view after taking into account the crop factor. Personally, this is quite a nostalgic focal length that I resonate with a lot, as it offers a very natural perspective to the eye. It comfortably sits between the classic 35mm and 50mm focal lengths, balancing both depth and wider geometric distortion well.
Logically, to keep the size of the lens so small and handy without a weight penalty, there have to be some compromises. The most obvious one is a constant f/4.5 aperture. There is also no manual focusing ring, which makes sense since the lens is too slim to allocate a barrel that would be comfortable to use while still providing enough space that doesn’t rotate for gripping when mounting the lens. So, you will be entirely reliant on autofocus when using this lens.
Build Quality
Despite being a cheap lens, it actually feels reasonably solid. This is largely due to the fact that there are no moving parts on the exterior of the lens except for its sliding lens cap. The entire lens body is made of plastic but feels quite premium, as if it were made from “posh” plastic. To further elevate its build quality, Viltrox has also decided to include an aluminum alloy mount to ensure durability for long-term reliable performance.
The elements inside the lens do rattle when shaken. This is because the lens uses a voice-coil motor (VCM) autofocus system that only holds the lens element magnetically when powered on. Viltrox issued a PSA warning for users not to close the lens cap when using the lens, as it may cause damage or malfunction to the motor. The sliding lens cap serves a dual purpose: protecting the front element and securing the internal lens group when not in use. Having a built-in lens cap also eliminates concerns about losing it.
Since the lens does not contain a floating element design, it uses the entire lens unit as its focusing mechanism, meaning the entire lens group moves in and out together during focusing. This results in a noticeable focus breathing effect when switching between near and far focus, but this is rarely a concern if you are just casually shooting images. Lastly, I also noticed that when the lens is not in use, the internal elements drop to their lowest point, protruding slightly from the lens mount. This is a downside for those who like to put their lens down on the mount side, as it risks scratching the back element.
Features
The Viltrox 28mm f/4.5 Fujifilm X-Mount features a 6-element, 6-group design, including two ED elements to minimize chromatic aberration and two aspherical elements to reduce distortion and improve image clarity. This optimization allows it to deliver consistent performance in such a compact size. Viltrox also claims that the front element is protected by a multilayer nano-coating that helps prevent dust, oil, and water from damaging the lens.
As highlighted previously, this lens has a fixed aperture, meaning there is no way to adjust the aperture based on lighting conditions. Therefore, you may need to increase your shutter speed in bright daylight, potentially requiring electronic shutter use. The lack of a filter thread to mount ND filters doesn’t help in this situation either.
The lens uses a voice-coil motor mechanism for autofocus, promising swift, quiet, and reliable performance—ideal for capturing spontaneous moments. It is also capable of focusing as close as 0.32 meters (1.05 feet), providing a maximum magnification of 0.11x. However, significant focus breathing occurs as the entire lens group moves, so this should be considered when shooting close-up subjects.
You can also find a USB-C port located at the bayonet mount, allowing for future firmware updates to ensure compatibility or even potential app control to expand usability.
Usage and Examples
Let’s be honest, lenses of this size will always come with trade-offs. In this case, the right question to ask is: are you willing to trade the fixed aperture for this focal length and autofocus? This lens is so small and light that I could almost forget that I had a lens on my camera, which is both good and bad. The good: no weight penalty for long shooting sessions. The bad: there isn’t enough weight for mass damping to counteract micro-movements.
The autofocus is pretty snappy and does not hesitate most of the time. Continuous autofocus is also silent and smooth since there are no moving gears inside the lens. However, when the lens hesitates to lock focus in backlit situations, there is no manual focus ring to override the focusing immediately, which can be annoying.
This might not be bad news for photographers looking for a nostalgic soft look when combined with Fujifilm’s film simulations, as this lens effortlessly produces a pleasing starburst effect. The overall sharpness of the Viltrox 28mm f/4.5 Fujifilm X-Mount is good, especially in the center of the frame, but leaves something to be desired near the edges despite being a full frame lens. Close-up performance for subjects within 2 m is also quite good, rendering details pleasantly.
Now, to address the elephant in the room: is the f/4.5 fixed aperture an annoyance? Depending on how you use it, it can be a double-edged sword. Knowing its strengths and weaknesses will help you leverage it to your advantage. Having a fixed f/4.5 aperture means you won’t accidentally blur everything with bokeh, but shooting in low light will be a challenge, as you’ll only be getting around t/6.7 after accounting for light loss in the APS-C format.
All things considered, this could serve as a camera body cap that doubles as a contingency lens when needed. However, for me personally, I struggle to see its practicality in my setup. It’s fun to play with, but it probably won’t be my main driver.
More sample images shot with Viltrox 28mm f/4.5 Fujifilm X-Mount on Fujifilm X-T5.
Summary
What I Liked
- Built-in sliding lens cap
- Small size, making the setup pocketable
- Lightweight, making it easy to carry without burden
- Quiet and precise autofocus performance
- Cheap price
- Great image quality due to full frame lens use on APS-C
- USB-C for future firmware updates
What Could Be Improved
- Variable aperture with a filter thread
- Reduced focus breathing
- A dedicated manual focus ring
- Fixing the rattling lens group and protruding back element
- Better coatings to improve contrast in bright light
There is this one question in my mind: how slim can an autofocus lens be before the compromise exceeds its benefits? I believe this lens sets the borderline. To be honest, there is little to dislike about the lens, especially when it is this cheap and small. Since this lens targets a pretty defined niche of needs, I can only think of two groups of people who may find it useful. One would be someone who needs something very cheap, small, and light. The second would be someone who primarily shoots in scenarios with ample lighting—though low-light work might be possible now, thanks to the high-ISO capabilities of recent cameras.
In short, this is a great lightweight travel lens to throw into your bag without thinking much about it. It’s not designed to be a workhorse lens, but it serves its purpose well for casual photography and everyday convenience. Its portability and ease of use make it a compelling option for photographers who want an ultra-compact setup without sacrificing autofocus capabilities.
Priced at just $99, the Viltrox 28mm f/4.5 is a great lens for photographers looking for a fun lens to play with or to make their current camera pocketable without breaking the bank.
