It's long been rumoured that Panasonic would launch a so-called 'full-frame GH5', which, as it turns out, isn't too far wrong: in early 2019 the company will release two full-frame mirrorless cameras in its all-new Lumix S lineup.

Called the S1 and S1R, here's all the details about the new system camera, its design, lens mount, lens roadmap, and how Lumix Pro will fit into the existing Lumix and wider full-frame mirrorless camera line-up.

Lens mount and lenses

  • Leica L mount lenses: Leica SL, TL, CL compatible
  • Micro Four Thirds (MFT) lenses not compatible
  • Panasonic, Leica and Sigma in lens alliance
  • Panasonic producing S lenses: 50mm f/1.4 at launch
  • Panasonic S 24-105mm and 70-200mm post launch

First things first: the all-important lens mount. Lumix S opts for the Leica L mount, which isn't perhaps a huge surprise given the format already exists, saves on production costs, and both companies have a long working relationship (there have been Leica-badged Panasonic compact cameras released for many years).

Plus, Leica, Panasonic and Sigma have formed a lens alliance, dedicated to the L mount, meaning each will produce their own lenses. Panasonic will make its own 'S' lenses, while Leica will continue to make its own L mount lenses (with SL and TL being its latest offerings).

Now, as Lumix S isn't directly related to Lumix G (the company's existing mirrorless compact system camera line-up, which uses Micro Four Thirds (MFT) lenses), there will be no compatibility with Lumix G. Indeed, given the sizing and proportions of both systems, we don't believe it would be physically possible to get an MFT lens to fix to the S mount and be able to deliver in-focus.

At launch that means the Lumix S1 and S1R will arrive with a choice of lenses from the off (there are eight Leica SL lenses already on the shelves at the time of writing). There will also be a Panasonic S 50mm f/1.4 with aperture control ring (which we've seen in person – and it's massive), with a 24-105mm (without aperture ring) and a 70-200mm (with aperture ring) arriving later down the line.

Panasonic promises to "develop more than 10 lenses by the end of 2020", too, to ensure its commitment to S.

Designed for pros

  • Viewfinder: 'higher quality than competitors' (details TBC)
  • Screen: tri-adjustable mount, touchscreen (details TBC)
  • Durable shutter: Over 200k cycles (figure TBC)
  • 100% weather sealed construction (to -10C)
  • Top display panel (with illuminator)
  • Single SD, single XQD card slots

The Lumix S1 and S1R look a lot like Lumix G cameras, just bigger... much bigger. Now, as this is a pro-targeted full-frame model, we wouldn't call the physical size a drawback. With one hand wrapped around the large grip, every finger has its own place, ensuring a solid connection to the camera, which will be essential with longer focal length lenses (even that 50mm felt larger than a Canon EF f/1.2 to us!).

Panasonic has had the Lumix S in strict lockdown ahead of its Photokina 2018 unveil, so images of the product are thin on the ground to say the least. Which is why we'll detail a little walkthrough to explain what you'll find and where.

Lumix S1: On the front

  • Two assignable function buttons between grip and lens
  • 1-2 switch (for two-form setup) to front corner (where AF-S/C would usually exist)
  • Front thumbwheel, embedded into grip (doesn't appear depressible)

That chunky grip has two assignable (and unmarked) Fn buttons embedded against the body. They take a bit of wrist wrangling to get them pressed, however, due to the sheer size of that grip.

Just like the Lumix G9 there's also a 1-2 switch to the front, to select between multiple setups. Handy if you're carrying one body only and shooting different scenarios and need a quick shift.

Lumix S1: On the top left

  • Full mode dial: P, S, A, M, iA, C1, C2, C3, Movie
  • Drive mode: Collar around mode dial

The mode dial features all the usual culprits, although iA (intelligent Auto) is a bit of a surprise. There's also a depressible lock to keep the dial firmly in place. Surrounding this dial is a collar to select drive mode, with single and stages of continuous shooting and intervals available.

Lumix S1: On the top right

  • Light-up display panel with relevant info
  • Separate WB, ISO and Exp Comp button trio
  • Rear thumbwheel (circular, overlaps rear)
  • On/Off switch

Other than promising a built-in electronic viewfinder (EVF) to beat all its rivals (we have no more details than that at present), and a tri-adjustable touchscreen to the rear, we don't have more specific details just yet.

The S1 is a lot more DSLR-like in its setup. With a dedicated trio of buttons to control WB, ISO and Exp Comp, in conjunction with the large rear thumbwheel, access is at your fingertips. We don't know if these marked buttons will double-up their functionality, but doubt this will be the case.

Showing all current settings is a small LCD panel, with separate illumination light, ensuring you can see all the necessary details when working in the dark.

Oh, and the on/off switch is a chunky, proper switch, that's for sure.

Lumix S1: On the rear

  • Lock switch (locks all controls to avoid accidental presses)
  • Playback button (left); Back, Disp., Delete trio (lower right)
  • AF-S/C/MF is a rotational switch surrounding the AF select button (upper right)
  • Joystick toggle control (upper right, near AF controls)
  • Q Menu (designated 'Q'), Menu/Set button to centre
  • Movie record button (by viewfinder)
  • Rotational d-pad (TBC)

To avoid accidental presses and unwated results, there's a large 'Lock' switch to the left side of the camera (if it was raised to your eye in use). That'll be useful to stop the touchscreen jumping into action.

Autofocus controls are handled by a dedicated button for AF Area/Type, while a rotational collar around this handles single and continuous autofocus or manual focus. A toggle to the side looks ideal for making adjustments, much like that of the Lumix G9 (but much better positioned; it's more open).

We're quite surprised to find a dedicated Movie button on the rear, particularly as there's a Movie mode on the main mode dial. It's well out of the way, though, right by the viewfinder, so should be difficult to press by accident.

Image and video quality?

  • Lumix S1: 24-megapixels / Lumix S1R: 47-megapixels
  • All-new full-frame sensor and Venus Engine
  • Video: 4K60p maximum (HDMI out TBC)

Thus far we've only seen a solid block mock-up of the S1R, with no moving parts (well, the lens was removable), so we wouldn't even suggest that we've seen any images from this camera yet. Therefore we don't know what the quality will be like.

What we can say, however, is that Panasonic refused to comment on whether this was the company's own sensor ...which suggests to us that it's not. The company has made Micro Four Thirds sensors for years, but it's most likely more business savvy to get another company to create the S1 and S1R sensor under specific request.

Savvily, the Lumix S will come in 24MP S1 and 47MP S1R varieties, targeting different kinds of pro users. Panasonic hopes to release both models simultaneously, rather than staggering launch (like the recent Nikon Z).

On the video front there will be up to 4K capture at 60fps, making the Lumix S a formidable player in the movie/videography department. Other details are scarce for now, however, but we would think clean HDMI out and all the must-have formats will be supported, along with sound recording/monitoring (all ports were sealed on the mock model we saw, thus it wasn't possible to verify).

Lumix Pro: Worldwide support network

  • Membership: Basic, Silver, Gold, Platinum, Black
  • Support in: USA & Canada / Japan / Europe
  • Free sign-up for 1 year (TBC)
  • Price structure TBC

The last part of the package is worldwide support. As Lumix S is targeted at pros, Panasonic is introducing Lumix Pro, a dedicated network for its users.

This tiered system will offer different privileges and benefits depending on level, but the highest level (which may not be a purchasable tier, much like you'll find with airline carriers' rewards systems) will offer worldwide support in Europe, US, Canada and Japan. That could mean, for example, that if you break a lens while on a shoot in Tokyo then a phone call ought to get Panasonic to fix it.

Exact benefits per tier aren't detailed at this moment in time, so it's all speculation for now. But what's clear is that Panasonic is looking to run a system to rival or better Canon Professional Services (CPS) or Nikon Professional Services (NPS). The pros out there will know exactly what they'll want and what's worth paying for, so it'll be interesting when full and final details at launch in 2019.

What about the competition?

Well, 2018 really has been year of the full-frame mirrorless, so Panasonic knows it's got a lot of competition on its hands. Both the Canon EOS R and the Nikon Z launched already, giving them a headstart over the Panasonic's 2019 kick-off.

That said, Panasonic is 10 years into Lumix G, so it knows what it's doing. Pros are already using the GH5 and G9 and other cameras for both stills and movie work. Plus the Leica L alliance will mean more lenses are likely to appear in a shorter period of time than its competition. Plus, with no DSLR business of its own to cripple (something Canon is acutely aware of, almost nervous about), the Lumix S just slots into the top of the system, leaving Lumix G to continue doing its thing.

Maybe, just maybe, all that'll be enough to hold people away from Canon, Nikon and Sony. From what we've seen and heard, the Lumix S1 and S1R will be formidable mirrorless full-frame cameras. Just how good, well, we'll have to wait until early 2019 to see.