Xiaomi Wants to Make Modular Magnetic Lenses for its Phones

Just before Mobile World Congress 2025 opens up in Barcelona, Xiaomi presented a concept it’s calling the “Modular Optical System”, which is basically an external lens that can attach to one of its phones.

Update 3/3: An earlier version of this article stated that there was no apparent pixel-binning in use by this prototype camera. However, as it turns out, the prototype can do typical four-in-one pixel binning to improve image quality in low-light.

This isn’t a lens on top of the phone’s own glass. It’s a standalone sensor-integrated lens module that magnetically attaches to the back of a phone. In this case, Xiaomi showed PetaPixel a modified Xiaomi 15 smartphone with built-in Qi2 magnet (like MagSafe on iPhones) that enabled the lens to stay attached.

Through two small pins, the lens “locked” into place to draw power from the phone’s battery. A small receiver using the company’s proprietary LaserLink technology connects it to effectively run as an additional lens within the camera interface. That means access to all the various modes and Leica processing embedded in the app. I took it for a brief test drive to see what the experience might look like with a finished product.

Bigger Sensor, Bigger Glass

This is a conceptual prototype, so while not finished, it felt more polished than I expected. The idea behind it isn’t all that new, though. Sony attempted something similar back in 2014 with its QX series of sensor-integrated lenses that acted more like independent cameras. Rather than interface with the camera app, they had to work within Sony’s PlayMemories app. While Sony gave it a go with multiple models and varying focal ranges, it never really took off.

Samsung even took a radical approach (for the time) in 2013 by blending together a Galaxy S4 phone with a point-and-shoot camera in the form of the Galaxy S4 Zoom. DxO One was another that doubly acted as a grip connected to the iPhone via a Lightning port. The Olympus Air A01 integrated a phone mount to act as a live view for the module.

In 2016, Motorola took a chance with its Moto Mods series of modular attachments that could stay fixed to Moto Z phones via pins and magnets. A Hasselblad collaboration brought the True Zoom Moto Mod and a 10x optical zoom with a 25-250mm equivalent focal range. It, too, didn’t take.

Xiaomi’s attempt here is a nod to all of them. One of the challenges those previous products faced (among others) was their smaller image sensor sizes. Xiaomi’s Modular Optical System uses a 100-megapixel Light Fusion X Micro Four Thirds sensor, making it considerably larger than the average phone camera sensor, including the Type 1 sensors Xiaomi uses for its flagships.

The lens is a 35mm f/1.4 with variable aperture going up to f/11, plus a manual focusing ring. Since there’s no aperture ring on the lens itself, you can only adjust stops in the camera app’s Pro mode. Autofocus otherwise works on all modes, and I could feel and hear the motor inside adjust to whatever I tapped onscreen to focus on. It’s also not clear if the final lens design would include a thread to screw in filters. This prototype doesn’t.

As for the glass, it’s a 6G aspherical lens structure and short-flange distance design with front-aperture configuration to try and keep the 100-gram weight down. It’s not especially big relative to the phone’s size but certainly stands out by its juxtaposition next to the rear camera module.

Using the Modular Lens

Applying the lens to the phone isn’t hard — a red dot at the top is the main visual indicator about orientating it the right way — it’s just not a one-and-done process every time. I always had to look to make sure I aligned everything the right way in my brief time with it. A second click after the magnet attached always indicated the pins were in place.

When connected to the phone, an icon appears on the camera app. Tap it and it switches the live view to the modular lens, and is the only time it actually draws power from the phone’s battery since it’s basically off otherwise. It’s impressive to start up and be ready to shoot in a few seconds, but I can see situations where that brief interlude could cost a great candid shot. One thing to note is the lens offers a crop factor for a 50mm equivalent when selecting 2x on the camera app.

Still, I was surprised at the lack of latency and lag when shooting. I couldn’t really tell the difference between snapping a photo with and without the lens, perceiving no other discrepancies in processing time, either. Xiaomi reps told me the 10Gbps optical transfer rate is the main reason why, as it transmits data through the lens to the phone’s image signal processor in “nanoseconds” without compromising quality. In effect, the lens isn’t processing images on its own but rather passing them on to the phone’s own imaging pipeline — a key difference compared to previous external integrated sensor models.

Manual focusing offers a satisfying click with each granular move helping to really fine-tune composition. It’s not a true macro lens, however, given it can’t focus on anything closer than 30 centimeters, but it is possible to makeshift your way into something if you shoot at full resolution in Pro or Ultra HD modes and crop afterward. The lens takes over for the main camera, so switching to the telephoto or ultra-wide cameras don’t involve it. Moreover, the lens’ protrusion from the back actually makes it visible in the frame when using ultra-wide.

The variable aperture is broad enough to enable photos that just aren’t possible on phones in certain situations. Try to do a long exposure during the day and you’re stuck unless you use special modes with software processing to plug the gap. This lens makes that considerably easier by just adjusting it in Pro mode and then setting up a lower shutter speed and ISO. I didn’t get the chance to really try it considering the limited time and space I had but it should be a noticeable change.

There is four-in-one pixel binning, which should improve image quality in low-light situations at the expense of megapixels and resolution.

Xiaomi claims the lens will be great for action and candid shots, though again, I didn’t have a real opportunity to test that with the few photos I captured in the hotel suite. Those results would have more to do with the phone’s ISP anyway, since faster shutter speeds and open apertures are easy enough to manage on its phones. Fastshot mode works the same as always, only it’s not clear how the different focal ranges within the mode apply to the lens.

A System, Not Just a Lens

Xiaomi is thinking this lens is more of a gateway to the broader Modular System. Other lenses at different focal lengths are one possibility, though the company is considering other accessories as well. The MagSafe ecosystem is already large, but it’s the pins and LaserLink that would enable such accessories to interface with the phone’s software in ways pure magnetic gear can’t. That future Xiaomi (and other Android manufacturers’) phones will have Qi2 magnets built-in is probably inevitable as early as later in 2025, but not everyone likes to take photos or record video with a naked device.

That’s the challenge Xiaomi faces with phone cases. It needs to figure out how to route the pins and LaserLink through a case to enable the same functionality without one. For a company that’s gone as far as making mobile photography kits for its Ultra lineup, that’s a hurdle it has to get over.

Not only that, but once applied, the lens makes it difficult to use accessories like gimbals or tripod mounts — unless you reverse the grip which then covers part of the screen’s live view and onscreen controls. Plus, its added weight might throw off a smartphone gimbal’s calibration. Even if you used a MagSafe tripod or stick with magnets on both sides, you can’t put it between the lens and phone because it would sever the power and LaserLink connections.

What About Leica?

What’s interesting is this is an entirely in-house endeavor. Despite its solid partnership with Leica, Xiaomi’s reps said they haven’t worked with the German camera brand on this at all. When I asked why, Xiaomi said it was open to collaborating on the Modular System but has only been under development in China thus far.

That’s a little surprising when looking at the lens’ size, which is very much in line with Leica’s glass and heritage in optics. Xiaomi’s flagship and mid-range phones already use Leica Summilux and Summicron lenses, so it’s not a stretch to imagine something collaborative coming out of this.

This is just my take, but I suspect price may also be a factor. Leica lenses aren’t cheap and I imagine neither is the expertise coming out of Wetzlar, Germany. Xiaomi doesn’t have an estimated price for this lens, nor even a timeframe it’s sharing on when it might release it, but it’s an added cost to a phone by any measure.

Mobile photographers looking for a larger sensor might find this lens appealing as a lightweight alternative to using a mirrorless camera in the field. Backward compatibility with current models seems unlikely given the lens systemic makeup as it doesn’t use Wi-Fi or Bluetooth, so the Modular System would need to launch as part of Xiaomi’s next generation of phones. We’ll be waiting to see if or when that happens.