Panasonic rocked the photo industry when it announced a partnership with Leica and Sigma to develop full-frame mirrorless cameras using Leica's existing L-mount lens system. Panasonic promised to release two cameras to kick things off, and we've been waiting patiently for details since they were teased last September at the Photokina trade show in Germany.

Today, the company announced just about everything we want to know about the new system—technical details on the two inaugural bodies, the S1 and S1R, along with information on the first three lenses which will go on sale.

The Cameras

Panasonic is bringing two cameras to market to kick things off. The two share a lot of technology, including absolutely identical body designs. The big differentiating factor is the image sensor. The S1 sports a 24MP sensor, while the S1R is designed for high-resolution capture with a 47.3MP sensor.

Both cameras sport 24-by-36mm image sensors, the same size as a 35mm film frame. This matches a recent trend in the industry—smaller sensors still have their place in the market, but more and more enthusiasts are joining pros by investing in full-frame hardware.

The cameras are built to endure, with dust and splash protection, a magnesium alloy frame, a 400,000-cycle mechanical shutter, and a freezeproof design. Dual card slots—not found on competing models from Canon or Nikon—support high-speed XQD and UHS-II SD cards. The XQD slot will receive CFexpress compatibility via a future firmware update, increasing its transfer speed capabilities dramatically.

Both models feature in-body image stabilization (IBIS). As with similar systems from other camera makers, any L-mount lens will enjoy the benefits of stabilization. If a lens has its own optical stabilization system it will work in conjunction with IBIS. Internal stabilization is rated for up to 5.5 stops of compensation, and can go up to 6.0 stops when paired with a stabilized lens.

Mirrorless cameras use electronic viewfinders, and the specifications of the EVF included in the S1 and S1R is very impressive. Its magnification isn't the absolute biggest we've seen, but at 0.78x it's competitive with others, and the OLED panel has more resolution (5,760k dots) than any other to date.

The rear LCD is a 3.2-inch LCD with touch support, 2,100k-dot resolution, and what Panasonic is calling a triaxial tilt design. It can face forward or down, and tilt out to the side. But, much like the LCD design found on the Fujifilm X-H1, it doesn't face all the way forward.

Other physical features of note include a focus selector joystick on the rear, a dedicated dial to adjust the continuous drive setting, and a monochrome information panel on the top plate. There's no in-body flash, but both cameras sync at up to 1/320-second with external flashes.

Imaging and Video

The expected imaging and video features are included. Both cameras can capture photos in JPG or Raw format, and record video at 4K—those are all basic expectations these days. Both models also support very high ISO capture—the S1 can crank as high as ISO 204800, and the S1R goes to ISO 51200. Both sensors start at ISO 100 natively and work at ISO 50 in a low extended mode.

While Canon, Nikon, and Sony all use some sort of phase detection focus in their respective mirrorless systems, Panasonic does not. It is sticking with the contrast-based Depth From Defocus (DFD) system found in its Micro Four Thirds series. The system is typically very fast to acquire focus, but doesn't do as good a job at tracking high-speed targets as phase detection. Because of this the S1 and S1R slow from 9fps to a more conservative 6fps when tracking moving targets in AF-C mode.

If you can skip shooting in Raw format, you can rattle off 6K (18MP) JPG images at 30fps or 4K (8MP) images at 60fps, although don't expect the camera to keep up with moving targets at those speeds.

Both cameras support a multi-shot, high-resolution capture mode for still subjects. It requires you to lock the camera down on a tripod, but if you need to get the most detail out of a landscape shot it's worth it. The S1 supports 96MP imaging and the S1R goes to 187MP, both in Raw format, when using the High Resolution mode.

The S1 and S1R support HDR image capture, a fairly nascent technology in consumer cameras. It leverages the HLG (Hybrid Log Gamma) HDR standard to capture 8K (7,680 by 4,320) photos with the S1R or 6K shots (5,888 by 3,312) images with the S1. Both formats use the 16:9 aspect ratio, as they are intended to be viewed on 4K televisions which support the HLG standard.

The big video feature is 60fps (59.94p) capture at 4K resolution. Both cameras support it, at 150Mbps with 4:2:0 8-bit LongGOP compression and LPCM audio. You can also roll at 100Mbps at 29.97p or 23.98p with AAC audio. You can also roll at 1080p, although you'll lose support for 24fps speeds by doing so. Slow-motion is available at 1080p as well, at your choice of 120 or 180fps capture for 30fps playback.

The S1's 24MP sensor does one thing the S1R's 47MP chip can't—record 4K footage at 10-bit quality. It supports HEVC HLG capture at 29.97p or 23.98p with 72Mbps, 4:2:0 LongGOP compression. Additional video features, including support for a flat V-Log profile, can be added to the S1 via a paid firmware update.

The Lenses

The S1 and S1R can both utilize the L-mount lenses already on the market—Leica has several full-frame and APS-C lenses on sale already. But not everyone wants to pay Leica prices for glass.

Panasonic is launching the system with two zooms and one prime. The basic starter lens for most buyers is the Lumix S 24-105mm f/4 Macro O.I.S. It's joined by the Lumix S Pro 70-200mm f/4 O.I.S. and Lumix S Pro 50mm f/1.4 join it.

Pricing and Availability

Panasonic plans on getting everything into stores in early April. Pricing is a little higher than what we've seen from others, with body-only pricing for the S1 coming in at $2,499 and the S1R at $3,699.

The 24-105mm zoom costs $1,299.99, with the 70-200mm coming in at $1,699.99 and the 50mm f/1.4 at a sky-high $2,299.99.

There are discounts available if you buy a camera and lens together. The S1 sells for $3,399 when bundled with the 24-105mm zoom, and the S1R kit is priced at $4,599.

Finally, an add-on battery grip is available. It works with either camera and costs $349.

Keep an eye out for more coverage when we've had a chance to use and test the new cameras and lenses.