Panasonic's much-leaked new camera, the GH5S, is now in the public domain. It sacrifices pixel count for sensitivity - for very good reasons. We've seen it and the pictures are impressive.
Still cameras that could also shoot video started the "cinematic video" revolution ten years ago. Things have moved on since then and now it's easily possible to buy a very good 4K dedicated video camera for the same sort of money that a DSLR with extensive rigging and a sound system would have cost.
So you would have thought that the DSLR/Mirrorless type of camera would have little interest for video makers these days.
While this is mostly true, there are some impressive exceptions. Sony's A7S series of cameras shoot 4K full frame video in lighting conditions that would baffle far more expensive, "more professional" cameras. And Panasonic's "GHx" range is hard to beat for picture quality at the price.
This time last year, the GH5 was revealed. It was the first mirrorless camera to offer 4K 50p/60p recording: an astonishingly capable video camera in the shape of a mirrorless still camera. And it will continue to be sold, at a lower cost than the GH5S.
Panasonic has a huge range of products The relationship between them is not always obvious. Helpfully Panasonic explained their taxonomy of high quality mirrorless cameras for us:
"GH5 is the ultimate Hybrid camera (equally at home with stills and video).
G9 is the ultimate photography camera
GH5S is the ultimate video camera"
We were also told that 52% of GH5 owners use it as a video product. We always suspected as much.
The new GH5S was designed for independent filmmakers but is also pitched at major cinema film makers as a "B" camera. It lacks the GH5's in-body image stabilisation and doesn't have the 6K "photo mode" - because the sensor doesn't have that many pixels.
But the new sensor does have pixels that are 1.96 times bigger than those on the GH5.
The sensor has a dual native ISO: 400 and 2500 (spot the Varicam heritage here!). If this ability is anything like the way it works on the Varicams, then it is a very big plus for the new camera. It’s an amazing thing: there really is no noise penalty working at the higher of the two native ISOs. Quite how this works isn’t completely clear, but I’ve heard reports that it involves having two separate A/D conversion systems on the sensor, one of them running at a higher voltage. All very vague and I’m sure there’s more to it than that - or everyone would be doing it - but if that’s the basis of it, it does sound plausible.
The new camera has an unlimited video recording time, a 4K photo mode and Timecode in and out. It will support simultaneous internal and external recording, and on-board capture is ten bit.
The V-log is included as standard. HLG is available in "Creative Video Mode".
The GH5S will support 4:3 anamorphic recording.
Sony's A7S was a bold and largely successful effort to build a full-frame mirrorless camera that was happy to shoot in low light conditions. It's been successful as a commercial product for Sony and it its role as a low-light camera that can shoot cinematic images. It achieved this through a well-understood engineering principle.
There's a certain inevitability in designing a low light camera. Noise is the enemy, and it's caused by the pseudo-random way that photons arrive on a camera's sensor. In good light, there are so many photons that there's no ambiguity about the light level. In low light, or if a sensor's pixels are too small, not enough photons will arrive in a given period to give a reliable average. So adjacent pixels, even if pointed at the same colour, will give randomly different results.
Bigger pixels reduce this problem, because they increase the likelihood of capturing photons on any given pixel. But you can't fit as many big pixels into the same space as smaller pixels. This is what has to give way: resolution.
And this immediately brings us into some deeply controversial territory.
On the one hand, more pixels are better, giving a smoother, more natural picture. On the other, smaller pixels are prone to more noise. You'll get better images (better colour, better contrast with lower noise) with bigger pixels, but they won't be as detailed or smooth.
You simply have to accept the pluses and minuses of each approach.
Panasonic claims that the GH5S is its best ever Lumix. It's certainly built like a professional video camera. The sensor is a brand-new 10.2 megapixel Digital Live MOS device and is supported by a Venus Engine DSP system. This is an even lower resolution than Sony's A7S, which has 12 megapixels, but remember that 4K needs only a resolution of 8 megapixels.
For most purposes the low pixel count of this sensor reminds us that you can take perfectly OK pictures from around 8 megapixels upwards.
Panasonic claims a maximum ISO of 51200. That's extremely useful and of course it's not that you can shoot videos at such extremes that matters necessarily but that you can capture good looking footage way beyond the normal limits. It's always hard to talk objectively about low light shooting because there will always be some noise, and the amount (and the quality) of that noise will be acceptable to some and not others.
I have seen the pictures. Panasonic brought us to their HQ building south of London just before Christmas. We were shown some pretty forensic analysis and comparisons with other cameras.
My impression was that in low light, the GH5S is a significant improvement over the GH5. Street-lit scenes had more colour in them. Skin tones looked more real and less washed-out. Highlights were better and less blown-out.
I would have liked to have seen more daylight footage away from the influence of sodium street lights, but we were shown enough variety that I was able to conclude that the new camera is a very worthwhile improvement over the GH5. In comparison with the Sony A7S, the GH5S's colours were more solid and had greater warmth. The Sony is, of course, Full Frame while the Panasonic is MFT and what a camera looks like at extremes is not always a good guide to how it will behave in normal lighting.
It's easy to see when Panasonic has gone down this route. While it's tempting to think that Panasonic has in the loosest sense "emulated" the formula in Sony's A7S in that it has made a more sensitive camera by making a lower resolution sensor with bigger pixels, this is no more a case of copying than it would be to make a faster car by putting a bigger engine in it.
What's more, Panasonic has in-house skills in low light video cameras with the Varicam range and the EVA-1, all of which feature dual native ISO and an ability to shoot in low light.
The GH5S's ability to record ten bit 4K video internally is an increasingly significant factor in this competitive field. While eight bit video can look very good, it's generally accepted that ten bit video is needed for grading.
The GH5S will ship on 12th January, costing £2119 including VAT and it's hard to see this being anything other than a huge success for Panasonic.
See Panasonic's full press release over the page.