It's a rare thing for an all-new camera format to appear, but Fujifilm is pushing into digital medium format with the announcement of its mirrorless GFX line and GF lenses.

The Fujifilm GFX 50S is the first camera announced in the line, complete with a 51.4-megapixel sensor that's 70 per cent larger than a full-frame DSLR's sensor. That's a whole lot more size to benefit from resolution and depth of field effects.

The GFX is interesting for a number of reasons. One, it's mirrorless, so there won't be any mirror slap when taking images and, therefore, this ought to negate any sharpness loss that can occur in higher-resolution cameras. Two, it's small and lightweight by medium format standards - as its 800g body attests. Three, it's super quiet in operation.

A new sensor needs a new mount, of course, with the new GF lenses arriving initially in 63mm f/2.8, 120mm f/4.0 macro and 32-64mm f/4.0 zoom flavours (remember the crop factor is around 0.8x, making 63mm around 50mm in full-frame (35mm) format). An additional three optics will join the line-up within a year of availability.

With a sensor measuring 43.8 x 32.9mm, Fujifilm hasn't opted for an unusual X-Trans array as it does with many of its mirrorless cameras, instead sticking to a typical colour array.

With such a large sensor and so much resolution the GFX 50S can benefit from shooting in multiple aspect ratios without losing a huge amount of resolution. Want 16:9? That'll come in 38-megapixels straight from camera. Same with 1:1 square ratio. And there are all manner of other options, too, from 5:4 to 6:9 and beyond.

The 50S is smaller than you might expect a medium format to be, while embodying some great design concepts: the vari-angle LCD is there for waist-level or overhead work; but in the box there's a viewfinder included. And it's no ordinary viewfinder: this clip-on inclusion merges beautifully with the body, but can also be angled through vertical and horizontal rotations to almost any given angle. Very clever.

But if you want big then you've got to pay big. When it's out in the first part of 2017, Fujifilm predicts that the GFX 50S will cost sub-$10,000 with the 63mm lens included. For an all-in-one kit that's not bad going, if, of course, you've got a spare £7,500-odd knocking around.