(Pocket-lint) - An image of the alleged Xiaomi Mi 10 Ultra appeared on Twitter, showing off the incoming top-spec phone's camera unit. And, claims the Tweeter, @RODENT950, it's going to feature a 120x zoom.

Clearly Xiaomi has Samsung in its sights - the latter having launched the S20 Ultra with a so-called 100x 'Space Zoom' - as this is the Chinese company's way of looking to outdo its Korean competitor.

However, let's break this down into its component parts. The numbers on the camera unit say 12-120mm 1:1.85-4.1 ASPH.

The 12-120mm is the equivalent focal length: here we can assume the 12mm is the ultra-wide lens, the 'standard' wide lens is most likely to be 24mm, therefore the zoom lens is most likely to be 5x optical, matching the 120mm equivalent (sometimes there's some rounding up of figures, thus this 5x might be 4.8x - something that's already prevalent in smartphones today).

The aperture is f/1.85 for the widest angle optic, progressing to f/4.1 as the 5x zoom lens kicks in.

And the ASPH? That's to outline it's an aspherical lens element, used to counter distortion and keep quality in check.

So where does the 120x zoom come from? This isn't a confusion between 120mm and 120x - both are shown in the image - rather it's the way that Xiaomi will derive this zoom from a combination of those three lenses and, but of course, a lot of digital zoom.

In essence it's like applying a 10x digital zoom to the maximum available - the quality of which, we suspect, will be very limited, just as it was on Samsung's S20 Ultra results.

Something to be excited about then? Well, probably not. It's all about big number headlines. Xiaomi has our attention, but how well the Ultra will pull off its 120x - which is a 1200mm equivalent here - we will just have to wait and see.

Writing by Mike Lowe.