Panasonic S1 review: A perfect camera, except for its autofocus system

Panasonic is last to the full-frame mirrorless fight, but it's coming out swinging. In February, it unveiled the S1 and S1R cameras and both of them are tough, beastly models with impressive feature sets. The 24.2-megapixel S1 I'm reviewing here is the more affordable at $2,500, but it's also the most versatile, aimed equally at photographers and videographers. Feature-wise, it lines up closely with Sony's A7 III and the new Nikon Z6.

The spec sheet is packed with things like 5-axis in-body stabilization, 10-bit internal 4K recording, a stellar electronic viewfinder and dual card slots. I had concerns about the price and autofocus system, however, so I was very curious to see how it stacked up against its main rivals in a full review. Now, let's find out.

Since the S1 is the first camera in an all-new system for Panasonic, we need to talk about the lens mount. Rather than creating its own, Panasonic formed the L-Mount alliance with Leica and Sigma and adopted the mount Leica uses for its full-frame SL and APS-C TL cameras. It's relatively large with an inner diameter of 51.6 mm and flange depth of 20.0 mm. That's important because it will allow Panasonic to design very fast and very sharp lenses.

Panasonic launched its full-frame system with three lenses, a 50mm f/1.4 prime and a pair of zooms, the 24-105mm f/4 and 70-200mm f/4 models. Thanks to the L-Mount alliance, however, that situation is going to change quickly. Sigma will launch no less than 14 prime L-Mount lenses in 2019 ranging from a 14mm f/1.8 ultra wide angle prime to a 135mm f/1.8 model, along with a macro lens. It will also sell an adapter for Sigma's own SA mount and Canon EF lenses.

Let's be clear about one thing: The Panasonic S1 is big and heavy. Weighing in at 1,021 grams with battery and memory (2.25 pounds), it's heftier than Sony's A7 III by 371 grams (0.82 pounds) and even outweighs Nikon's D850 DSLR by 100 grams or so. I could really feel the size difference between the S1 and its direct competitors like the Nikon Z6, Canon EOS R and A7 III.

I wish it was smaller because I often need to lug gear around trade shows and on the streets. But the size has some advantages, and when you see the technology Panasonic packed in there, the extra pound or so is worth it.

It has a weather-sealed body that feels very rugged and a huge grip that makes it comfortable to hold for long periods. The S1 is covered with buttons and manual dials, letting you set things like the autofocus and burst shooting modes without diving into menus. It has a better control layout than any other mirrorless camera I've tried recently, including Fujifilm's excellent X-T3. Controls like the ISO and joystick toggle are even textured so you can find them by feel. It's just very easy to operate this camera without taking your eye from the viewfinder.

Speaking of, the Panasonic S1 has the best electronic viewfinder of any mirrorless camera, period. It's an OLED model with a 5.76-million dot resolution, 120 fps refresh rate and .005-second lag rating. It's brilliantly sharp and quick, making it possible to judge focus and accurately preview photos and video. For me, this nullifies any argument for an optical viewfinder, putting the S1 on an equal footing with DSLRs.

The rear touch display lets you control not only focus and other camera functions but the entire menu system, as well. It's sharp, responsive and reasonably bright, though it gets washed out a bit in sunny conditions, much like the display on the GH5. Both Canon and Nikon, I found, have brighter displays on the EOS R and Z6/Z7.

Camera menus are typically the worst part of many camera systems, but Panasonic has done a great job here. They're arranged logically, making it easy to find a given function, and are fully controllable via the touchscreen. Once you set up the customizable Q menu and buttons the way you want, you should be able to operate the camera without even touching the menus.

Unfortunately, the display only tilts up and down and at a 60-degree angle to the right, and not all the way around. I can't quite understand why Panasonic did this, as the GH5/GH5s both have fully articulating displays. The S1 will therefore never make a great vlogging camera, though you could argue that it's too heavy for that purpose anyway.

One of the main reasons for the extra size and weight is the 5-axis in-body stabilization (IBS). Alone, it offers an impressive 5.5 stops of shake reduction, compared to 5 on the Sony A7 III and Nikon Z6, and zero on the Canon EOS R. That means you can shoot -- conditions and luck permitting -- at 1/8th of a second and lower and still get a blur-free photos. In concert with stabilized lenses, you get up to 6 stops. Panasonic's goal was to match the IBS capabilities of the GH5, and it succeeded. Because the S1's sensor is so much larger, however, the IBS system needed to be very large and heavy. That's one of the reasons the camera is so big.

The S1 has two card slots, one SD UHS II and the other XQD. At first, I wondered why Panasonic would use different, incompatible systems, but it makes sense considering the dual use of the camera. Photographers who need a reliable backup can use both slots at once, while videographers can shoot on XQD. The latter is significantly faster, running at up to 440 MB/s, and will hit a blistering 1,700 MB/s when Panasonic brings CFexpress support via a future firmware update. That will make video recording more reliable and large file transfers faster.

As for ports, Panasonic hasn't skimped there, either. The S1 packs both headphone and microphone ports, and it will support XLR via a dedicated hotshoe, just like the GH5. You also get a fast USB Type C port and HDMI output to external recorders or monitors. The S1 supports both Bluetooth and WiFi remote control, and the new Lumix Sync app for remote shooting and photo transmission is actually pretty good.

Panasonic has stuck with its contrast-detect "depth-from-defocus" AF system (DFD) for the S1, rather than using phase-detect like all its other rivals. It does that, it said, to retain image quality, because phase detect pixels can add banding and other artifacts to photos in some (fairly extreme) shooting conditions.

The slight boost in image quality isn't worth the downsides of contrast detect, though. The S1 does feature a rapid .08 second focus lock-down time, and burst speeds of 9 fps in single AF mode, or 6 fps in continuous AF mode. That's not bad, but doesn't compare favorably with Sony's A7 III, which can handle 10 fps in continuous AF mode, even with eye AF turned on. On the plus side, using a high-speed XQD card you can shoot 90 RAW images without stopping and infinity ("999", according to Panasonic) JPEG photos continuously.

The S1 is also less reliable than Sony's A7 III, failing to lock autofocus at times. That results in a relatively low "hit" rate of usable shots, particularly during continuous shooting. The system tends to pulse, or hunt back and forth, to try to nail focus. That's particularly disconcerting when shooting video, as it can render some shots unusable. By comparison, Canon's excellent Dual Pixel system usually locks focus without any hunting, making it much more useful for video.

On the plus side, I found that Panasonic's subject-, face- and eye-tracking system works extremely well. Powered by deep-learning AI, it locks onto your subjects' eyes nearly instantly and can follow multiple people at once. I also tested it on animals, including chickens and dogs, and it had no problem tracking them, even when they went behind shrubs and plants.

Despite my issues with the contrast-detect setup, it's Panasonic's best auto-focus system yet and delivers good results once you get used to it. It's also highly tunable in terms of speed and tracking behavior, so you can adjust to find an optimal setup. Hopefully, Panasonic will continue to improve it with firmware updates to make it more predictable.

Other aspects of the S1 are also top-notch. The 5-axis in-body stabilization (IBS) system is excellent, maybe the best on any mirrorless camera. With all the space it takes up, it gives the sensor a lot of room to move and compensate for shifting or rolling movements. I found I could take photos without any camera blur at all, even at shutter speeds down to 1/8th of a second. It also performs beautifully for video, but more on that in a second.

A big camera requires a big battery, and the 3,050 mAh cell on the S1 is chunky indeed. Even then, it's only rated to power the camera for 400 shots, compared to 700 on Sony's A7 III. In normal use, however, you should be able to double that, particularly if you engage the power saving settings on the camera. Video endurance is very good, letting you shoot for about two hours on a charge. However, you'll want to order extra batteries if you buy this camera.

The S1, as you'd expect, is an excellent mirrorless camera for video, but I do have a few bones to pick with Panasonic. First, let's talk about what's good: The 4K video at up to 30 fps is razor sharp, because the S1 reads the entire 24.2-megapixel sensor and downsamples it to 4K size, delivering crisp shots with zero aliasing and moire. Panasonic has really stepped up its sensor game, delivering rich and color-accurate video. On top of that, there are no recording length limits at most resolutions, other than at 1080p 180 fps.

Once again, the in-body and hybrid stabilization does an incredible job of smoothing out video, even while you're walking -- provided you're not too herky-jerky. If the optical stabilization won't do, Panasonic also offers digital E-stabilization, which uses a slightly smaller portion of the sensor to give it more room to shift in case of extreme movements. Being quite hefty, the S1 also has lots of inertia to resist minor wobbles. Put together, this is a great camera for handheld video.

I was able to shoot very sharp, color-rich video with the S1, and the extra depth of field available with the full-frame sensor opened up new artistic and practical possibilities for me. For instance, I use the older GH5s to record a lot of review videos, but when shooting interviews, it's difficult to get a soft-focused "bokeh" background to isolate the subject. With the S1, that's easy to do even with the f/4 24-105mm lens.

Shooting indoors in dim light, I found that the S1 delivered incredible results. Shots were usable with noise being well-controlled, even at ISOs as high as 51,200. I think it actually delivers results close to Sony's A7S II, the current low-light champ, and I don't say that lightly. Another plus: Rolling shutter is well controlled, so you won't get the rubbery video on fast camera movements that you see on Sony's A7 III, for instance.

As mentioned, the S1 has both headphone and microphone jacks, letting you monitor your interviews and other recordings accurately. Internally it will record 4K video at up to 30 fps in 4:2:0 10-bit mode, but only at a limited 72Mbps bit rate. At higher frame rates, up to 60 fps, you can capture 4:2:0 8 bit 4K video internally with an APS-C crop. 1080p video can be recorded at up to 180 fps. Right now, you can only output external 4K video with 8-bit 4:2:2 detail, and there's no V-Log option to give filmmakers improved dynamic range.

The S1's video recording modes compare favorably to other full-frame models (for now). However, I feel that Panasonic has made a mistake here with the S1. Video recording falls well short of its own GH5s, which does have V-Log and can record 4K 10-bit 4:2:2 30 fps video internally, and output 4K 60 fps 10-bit 4:2:2 video.

Panasonic will soon give shooters the same options on the S1, namely 4:2:2 10-bit 4K 30p internal video recording, 4:2:2 10-bit 4K 60p HDMI output, and full V-Log recording. Unfortunately, it will charge you an as-yet unknown price for that update, on top of the $2,500 you already paid for the camera. That seems an odd choice considering that Nikon will soon unlock 12-bit RAW recording -- an arguably better feature -- for the Z6 and Z7 via a free firmware update.

Another issue with video: Any 4K shot at speeds faster than 30 fps is cropped to APS-C size. On top of that, in all high-speed shooting modes, there's no option for manual exposure -- only automatic. That can be a problem in changing light conditions, as you'll notice distinctive switches in the image if the camera changes the aperture. That can be especially problematic during tracking shots, where high frame rates are often used and lighting conditions can change.

The video autofocus system works as well or maybe a bit better than the one on the GH5/GH5s. As with photos, the tracking system is particularly good at keeping your subject's eyes and face in focus. However, the contrast-detect system does tend to hunt, so your subject will occasionally go in and out of focus. This is particularly noticeable on out-of-focus backgrounds, which sometimes "pulse" in and out of focus, ruining the shot. After I fine-tuned the settings, the problem largely disappeared, but it still cropped up from time to time.

If you'd rather do manual focus, as many videographers prefer, Panasonic's system uses a "focus by wire" electronic system. However, they've hit on a good idea with it. Some lenses will have a linear response thanks to a focus clutch and distance scale. Best of all, you can define the amount of rotation required to go from close to infinity focus, letting you set the precision level you prefer.

The Lumix S1 has Panasonic's most advanced color science yet, delivering excellent results for both RAW and JPEG photos. Out of the camera, JPEGs have rich, natural colors, particularly in the skin tone areas. RAW photos are captured with 14-bits of color, giving you plenty of room to boost shadows and reduce highlights in Lightroom.

The S1 has an all-new 24.2-megapixel sensor that differs from the chips that Sony manufactures. Instead of backside illumination, it uses tiny microlenses ("waveguides") to boost light on the photodiodes. As a result, I believe the S1 is far and away the best low-light 24-megapixel camera on the market. Noise is shockingly well-controlled at ISOs all the way up to 51,200 (but not at the expanded ISO 102,400 setting), with noise reduction that's not overly aggressive. The images I shot in my friend's hunting lodge, both of people and objects, are impressively clean and saturated.

Combined with the very effective IBS, the S1 really produces great images even in low light, and is only held back by the occasionally balky autofocus. The new full-frame mount allows for a much shallower depth of field to boot, so this should be a great camera for portrait photographers and artistic shooters.

Panasonic's S1 is the real deal, delivering both fantastic photo and video quality. In most areas -- including low-light sensitivity, stabilization and dual-card redundancy -- it stands up to and surpasses rivals from Sony, Nikon and Canon. The L-Mount system is also full of potential, and by next year, there could be a few dozen lenses available for it.

I think the big, heavy body is not actually a bad thing, as the ergonomics and handling are really good, and the extra heft helps with hand-held video shooting. Panasonic's redesigned menu system is top-notch as well, making it a snap to set up the S1 just the way you want.

The downside of the S1 is the contrast-detect autofocus system. It simply can't measure up to phase-detect systems on Sony, Canon and Nikon cameras in terms of speed and accuracy. It works fine under most circumstances but has trouble with continuous tracking and occasionally hunts for video focus.

Sony's $2,000 A7 III, the $2,000 Nikon Z6 and, to a lesser extent, Canon's $2,300 EOS R are the S1's biggest rivals. At $2,500 the S1 is the most expensive of them all. All things considered, I think the price is a bit too high -- especially considering the paid firmware update. Yes, it has dual card slots and in-body stabilization but Sony achieved both of those things at a lower price point. I think Panasonic also has tough competition with Nikon Z6, considering that model's much lower price and strong video capabilities.

The L-Mount system

Body

Performance

Video

Image quality

Wrap-up