In terms of form factor, we have had two styles so far: The first two cameras were quite small, but still had reasonable ergonomics. However, only one control wheel left quite a bit to be desired.
The Lumix GH3 introduced the larger camera body, and also deviated from the previously used oversized multi aspect ratio sensor. The larger body size allowed for a much better control layout, with three configurable control wheels. However, the eye level viewfinder (EVF) was not perfect.
The Lumix GH4 looks like it reuses the GH3 camera body, but there are in fact a lot of smaller changes which greatly improve the handling. Read about the changes here.
Timing of the next generation
To speculate about the launch of the next generation camera, the Lumix GH5, it is good to look back at the historic announcement times:
There was a two year delay from the GH2 until the GH3. The GH4 was announced somewhat faster, probably because Panasonic needed to prove that they were still the top mirrorless system for video use.
With the recent downturn in digital camera sales, I would expect that the GH5 is announced at least two years after the GH4. That is, February 2016 or later.
The next big tradeshow is Photokina on September 20-25th, and this is a probable venue for the announcement of the GH5.
On the other hand, one could ask: Why announce a new GH model now? The Lumix GH4 is a perfectly fine camera.
And it recently god a shot in the arm: In September last year, the V-Log L profile became available, making the camera much more usable for professionals. To learn more about what this is and how to get started using it, you can read this article.
However, as time goes, there are more and more features lacking from the GH4, which people would otherwise expect nowadays.
One major disadvantage of the Lumix GH4 is that is can only record 4K video with a crop factor: It does not use the whole sensor width. See this illustration:
This means that if you use the 4K video recording, you get an additional 1.3x crop factor: The Lumix X 12-35mm f/2.8, it becomes like a 16-46mm lens, or 32-92mm in 135 film equivalent terms. So you will often need wider lenses when using the 4K video mode.
The GH4 applied this crop to avoid scaling down the whole sensor output to 4K format. That would have required too much computing power. The Lumix GH5 will surely record 4K video from the whole sensor width, though, avoiding this additional crop factor.
On the other hand, both more recent 4k capable Lumix cameras (Lumix G7 and Lumix GX8) share the 4k crop strategy to avoid downscaling, so perhaps Panasonic don't have a solution to this problem yet.
Some have speculated that the GH5 will record even higher resolution video, e.g., 5K or even 8K. I don't think so. 4K is still a quite new standard, and many have still not upgraded their TV sets to 4K. So I think 4K will be the preferred format still some more years. There is still improvement potential inside the 4K video format, and that is what the GH5 will aim for.
What might happen, though, is that the GH5 could record 4K video at a higher framerate. Currently, the maximum framerate is 30FPS with the GH4. Today, that is only topped by some very expensive and bulky cameras, like the Sony FDRAX1 or Sony PMW-F55.
If Panasonic can release a GH5 with 4K 60FPS video recording, that would be a game changer on the same level as the GH4 was two years ago. However, this would require faster sensor readout, and it is not obvious that it is possible with the current technology level at this price point.
In addition to high quality video output, the GH5 will also get the latest in terms of features, that includes:
- 4K Photo. This mode was first introduced on the Lumix GH4, with the 2.0 firmware six months into the product life of the camera. Read about it here.
However, the 4K Photo implementation in the GH4 was quite basic, and is already surpassed by more recent cameras like the Lumix G7 and Lumix GX8.
- Post focus. A feature so far seen on the Lumix G7 and Lumix GX8. This allows the camera to scan through the focus range, and take one picture every time something in the frame is in focus. You can later select which photos you'd like to keep.
Unfortunately, this feature is limited to 8MP resolution only, only to JPEG, and the pictures are taken over some time period, not instantaneously, of course.
- The Lumix GH4 has the DFD, "Depth from defocus", meaning that it analyses the nature of the bokeh to guess how far off the focus is. This is based on a database of Lumix lenses. This technology can always be better, and I think the Lumix GH5 will still improve upon it.
The GH4 does autofocus during 4K video recording, however, the AF speed is very slow. This will certainly be improved with the GH5. Here you can see a comparison between the AF speed of the GH3 and GH4 in 1080p, and also the GH4 in 4K resolution.
- Electronic shutter. This is a very useful feature which allows you to take pictures silently, without the mechanical shutter. The downside is that the picture is scanned vertically fairly slowly. Anything moving during this time will cause "rolling shutter" effects, read about it here. The GH5 needs to further improve upon this sensor readout speed, for more reliable electronic shutter mode.
- Rolling shutter. In 1080p mode, the images are scanned in around 1/100s, which is fast enough that rolling shutter is not a big problem. In 4K mode, though, the frame is scanned much more slowly, around 1/30s, which means that rolling shutter can be a big problem if you are handholding the camera. If the GH5 ups the framerate to 60FPS in 4K mode, then rolling shutter will probably not be a problem anymore, as the image must be scanned twice as fast.
- Image stabilization. Some recent Panasonic cameras (Lumix GX7 and Lumix GX8) include In Body Image Stabilization (IBIS), which is a new direction for Panasonic. Seeing that recent Olympus cameras are capable of using this feature to stabilize also non OIS prime lenses, will Panasonic add this feature to the Lumix GH5? I think not. I think the GH5 sensor will need more cooling, which makes the IBIS setup harder to implement.Here is what the IBIS of the Olympus E-M5 Mark II looks like:
As for the form factor, I think the Lumix GH5 will be mostly like the Lumix GH4. The GH4 has a very good, ergonomic design, which is stable to hold and easy to use. I don't see the need for any major redesign of the camera body now.
Finally, the GH5 will get a higher resolution. Nikon recently moved from 16MP to 20MP for their top cameras, the Nikon D5 and Nikon D500. Also, Fujifilm went above 16MP for the first time with the Fujifilm X-Pro2.
With this development, Panasonic also need to move up from 16MP, and the GH5 will most likely get a 20MP sensor, just like the Lumix GX8.
If you are into a video oriented mirrorless camera, one obvious, and high end, choice, is the Sony a7S Mark II. This camera has everything you could wish for in terms of professional colour profiles, for the best post processing (colour grading). As it is a full frame camera, though, the lenses will be much larger, and also quite expensive. On the positive side, the camera does not have any horizontal crop factor when recording 4k video, unlike the Lumix GH4.
Another high performance choice is the Samsung NX1, which gives you a lot of features for the money. On the other hand, there are uncertainties to the future of the Samsung NX format, so this is a choice with some risk.
For somewhat less cash, you can get the Sony a6300. It is an APS-C sensor sized camera, so the lenses will be somewhat smaller. Avoid the 16-50mm power zoom kit lens, though, as it is rather poor. This camera appears to have the best continuous autofocus performance while recording video in 4k in this class. Certainly much better than the GH4, which is quite poor in this respect.