Almost all phones with optical zoom have the same problem. This Chinese brand believes it has solved it in a curious way

The greatest illusion trick in mobile photography is continuity between cameras. When we zoom from 1x to 5x on a telephoto smartphone, we are not moving lenses like on a camera; the mobile jumps between fixed sensors and fills the gaps with digital cropping and AI. The result is those sudden jumps in color and image in the viewfinder and a loss of quality in the “intermediate zooms” that we make when pinching the screen.

Tecno, the star brand of the giant Transsion—the fifth largest manufacturer in the world hot on Xiaomi’s heels in some markets—has taken advantage of its annual event to present two technologies that attack precisely this problem: a zoom that does not “jump” and a periscope that shrinks.

Optical continuous zoom. And from an increase, up to nine. The most ambitious proposal is the “Freeform Continuum Telephoto”. On paper, it promises to maintain optical sharpness throughout. It represents an important leap, although it is not the first: Sony tried it with the Xperia 1 IValthough its range was more limited. LG also showed similar concepts a few years ago, but no one had promised to cover the main angle lens to the long telephoto lens in a single module.

To achieve this milestone without turning the mobile phone into a brick, the Chinese firm moves away from the traditional design of lenses that move longitudinally. Instead, they turn to physical principle of the “Alvarez Lenses”: a system that employs two lenses with free-form surfaces that move perpendicular to the optical axis. By sliding one over the other from the side, they change the optical power of the set and achieve that zoom effect. This technology is related to recent reports that Samsung was developing cameras with continuous zoom for Chinese manufacturers.

A periscope that folds on itself. The second innovation presented by Tecno attacks the volume. We are obsessed with increasingly larger sensorsbut the space inside the mobile is finite. Periscopic telephoto cameras require a lot of space, but Tecno and its “Dual-Mirror Reflect Telephoto” promise to reduce the size of the module by 50% and its height by 10%.

• Instead of a simple prism that bends light 90 degrees, the system uses coaxial optics that bounce light multiple times inside the lens using reflective mirrors. It is what allows long focal lengths in a shorter physical distance.
• However, this design has a physical trace– When using a central obstruction, the bokeh is not circular, but rather takes on a donut shape. Tecno sells it as an artistic feature, the truth is that it is a consequence of mirror optics.

Battle against the accused. The new thing from Tecno comes at a time when mobile photography It depends a lot on the processing what are you looking for the photo instagrammable above realism. Going for better optics instead of digital cropping and AI rescaling seems to be the right direction to achieve naturalness.

However, we must maintain some caution. The challenge of this zoom is not only that it works, but that it is bright. Maintaining a decent aperture throughout that range is no easy task. If the system is too dark, the ISO will shoot up, generating noise that the software will have to remedy: back to processing. For the moment, we must wait to see if these concepts end up in a commercial mobile phone.

Images | Techno

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