First Impressions

Other than the red ring on the GH5S's drive mode dial and a big red 'S' on the front of the camera, there's little to tell it apart from its higher pixel-count sister model.

The first impression anyone is likely to have is just how similar it is to the regular GH5. The GH series had already settled down to the point that the bodies are pretty similar, but the GH5S is nigh-on indistinguishable from its higher pixel-count sibling.

Better still, the menu system is all-but identical too, which means any GH5 user can pick up the GH5S and start shooting after just the few minutes it takes to find the feature differences.

It should be a camera that's immediately familiar to GH5 owners, which is a good thing, as both cameras have been carefully designed to give access to their extensive video feature sets

Sadly, for anyone planning to occasionally rent a GH5S to shoot alongside their GH5, the camera settings saved by the GH5 can't be loaded into a GH5S. That's understandable, given there are settings unique to each camera but we'd love to see a way to sync common settings, particularly interface and button settings, between cameras. Still, it should be a camera that's immediately familiar to GH5 owners, which is a good thing, as both cameras have been carefully designed to give access to their extensive video feature sets.

One of the biggest differences between the cameras becomes apparent if you try shooting the GH5S side-by-side with the GH5: the multi-aspect sensor means you get a slightly wider angle-of-view with any given lens. Cropping a 16:9 region from a 4:3 sensor yields around a 1.09x crop in the diagonal angle of view, whereas the multi aspect design maintains the diagonal, which means using a larger sensor area than simple cropping, as well as a wider angle of view.

Panasonic Lumix DC GH5S
42.5mm lens
Sony a7S II
85mm lens

It's good to see Panasonic reviving its multi-aspect sensor design. This was an extremely popular feature on the GH1 and GH2, and its loss represented one of the few gripes videographers had with the GH3 and later models.

But what of performance?

To make sense of the GH5S's low light performance, it's important to understand what a reasonable expectation would be.

There are a few things that should help the GH5S in low light: its sensor's dual gain design, plus sophisticated noise reduction, with the possibility that larger pixels give those noise reduction algorithms a cleaner signal to work with. However, the Sony a7S II also has a dual gain sensor and large pixels, which is likely to mean the main difference is simply one of sensor size* and image processing.

When shooting UHD 4K, the a7S II uses a sensor region 3.6X larger than that of the GH5S**. In principle this should give the Sony an overwhelming advantage if both are shot using the same F-number and shutter speed, since it means the Sony's sensor will be exposed to 3.6x more total light. This is equivalent to a 1.9EV difference.

Panasonic Lumix DC GH5S
Exposure Matched [Rec709]
F5.6 | ISO 12,800
Sony a7S II
Exposure Matched [Rec709]
F5.6 | ISO 12,800

And, sure enough, particularly when shot at very high ISOs, that benefit is clear to see: the a7S II output looks much cleaner when shot at the same nominal exposure settings. However, this isn't always the case: another big difference between the two cameras is the GH5S's ability to capture 10-bit 4:2:2 footage, rather than the 8-bit 4:2:0 output of the a7S II. The difference becomes apparent in the Log footage.

Panasonic Lumix DC GH5S
Exposure Matched [Graded VLogL]
F5.6 | ISO 12,800
Sony a7S II
Exposure Matched [Graded S-Log2]
F5.6 | ISO 12,800

Shooting in Log is an attempt to squeeze as much of the camera's dynamic range into the limited space of the video files as possible, with the expectation that you'll color grade the footage later, stretching that data back out again. The Panasonic's greater bit depth means that it preserves the original data much better than the Sony can. Sure enough, when you stretch it back out you can see that difference. For Log shooting, 10-bit footage looks significantly better – particularly in these high ISO examples which probably didn't need to be shot in Log and have very noisy shadow regions.

It runs deeper

However, that's not the end of the story.

Along with the additional light capture of a larger sensor comes shallower depth of field, but that's not always desirable. There are times when shooting video that you need fairly deep depth-of-field. This can be when shooting close-up or for making sure your subject doesn't immediately fall out of acceptable focus if they move. In these circumstances you should be able to stop-down a larger sensor camera to match the depth of field of a smaller sensor camera, at which point both cameras will also receive the same amount of light for the same shutter speed and angle-of-view (there's no inherent depth-of-field advantage to smaller sensors).

Panasonic Lumix DC GH5S
Depth-of-Field Matched [Graded VLogL]
F7.1 | ISO 25,600
Sony a7S II
Depth-of-Field Matched [Graded S-Log2]
F14 | ISO 102,400

We've already seen the GH5S was pretty competitive against the a7S II at moderately high ISOs and when shooting Log, when shot at the same exposure settings. This means it races ahead of the Sony whenever you need the depth-of-field that the GH5S offers and have to stop the a7S II down.

Panasonic Lumix DC GH5S
Depth of Field Matched [Rec709]
F4.5 | ISO 800
Sony a7S II
Depth of Field Matched [Rec709]
F9 | ISO 3200

Then, of course, there's the GH5S's greater range of video tools, including vector scopes and waveforms, and its ability to capture great bit-depth video with better color resolution (10-bit 4:2:2 capture, rather than 8-bit 4:2:0 capture), and the GH5S suddenly looks like something of a bargain. Oh, and the small matter of being able to shoot DCI video and both flavors of 4K at up to 60p, neither of which the Sony can do.

So, while the GH5S doesn't overthrow the laws of physics by outperforming the a7S II, it comes a lot closer to matching it than sensor size differences alone would lead you to think possible. In many circumstances it comes close and in any situation where you need to maintain a certain depth-of-field, it can outperform the Sony.

Things we like

  • Multi-aspect sensor design allows larger sensor area and preservation of angle-of-view
  • Video-optimized sensor: fewer pixels mean less rolling shutter and allow video-appropriate anti-aliasing filter, to protect against moiré
  • Impressive low light performance helped by dual gain sensor
  • 60p shooting in both DCI and UHD 4K
  • Consistency of design and operation with GH5
  • VLog-L included by default and LUT-corrected display in playback
  • Features such as T/C in/out, and the ability to offer

Things we’d still love to see

  • As amateur film-makers, we would have loved to have seen an image stabilized variant
  • 10-bit 4:2:2 video across all frame rates would be amazing
  • Ability to share common settings between GH5 and GH5S

The GH5S builds on the specs of the best-specified stills/video camera we’ve ever encountered, so it’s probably no surprise that the only things we’d like to see added look like a rather fanciful wish list. We’re really looking forward to shooting much more with the GH5S: seeing how its autofocus compares with its sister model and experimenting with its Hybrid Log Gamma output. Until that point, it’s fair to say we’re very, very impressed.

* We say sensor size, not pixel size because, when scaled to the same size, there's rarely a significant difference in performance between using many small pixels and using fewer, larger pixels.

** The a7S II appears to use its full sensor width for capturing UHD 4K footage, which means a 36 x 20.3 mm region. We calculate the GH5S uses an 18.9 x 10.6 mm region, which is 3.6X smaller.