Saturday, 8 February 2014

GH4: The game changer

The big news this week is of course the announcement of the Lumix GH4, the new Micro Four Thirds flagship camera from Panasonic.


While the Lumix GH3 was more about competing with pro DSLR cameras, the upcoming GH4 has the most breaking news in the video area. More about that further down.



First, to put the camera announcement in context, let's look at the timeline:


The vertical lines are camera trade shows, where new gear is usually announced. Grey lines are the PMA (Photo Marketing Association) annual shows, and orange lines are the competing Fotokina shows in Cologne, Germany, every even year. We can see that Panasonic has grown more confident over the years, more often putting the announcements outside of the trade shows in the recent years.

Camera makers often skip the "4" number in product names, due to superstition in some Asian markets. However, top models often still use the "4" in the name, like the Nikon D4. And the Lumix GH4, it seems. Another reasons for not skipping the "4" is probably that the big new feature in the GH4 is 4K video.

Based on the timeline, we can expect that the new models G7 and GF7 will also be launched soon, probably this spring. Not that there is much wrong with the existing models G6 and GF6. They are both fine, feature packed cameras at an ok price.

Sensor


Most people seem to agree that the Lumix GH3 was the first Panasonic M4/3 camera to use a sensor from Sony, the same as is used on the Olympus E-M5. These details have not been officially confirmed, though.

The data sheet for a Panasonic sensor called MN34230PL has come up. You can see the it here. News have surfaced that the premium Olympus E-M1 camera uses this Panasonic sensor, which is quite surprising.

Some speculate that the GH4 will use this sensor. Based on the sensor specifications and the GH4 features, it does make sense. But this is of course still unknown.

There are still some differences in the sensor implementations, though: The E-M1 has on-sensor PDAF photosites, making it the only Micro Four Thirds camera so far which can focus Four Thirds lenses effectively, using an adapter. Also, while the E-M1 does away with the AA filter, the Lumix GH4 is going to have a fairly strong AA filter to avoid moiré.

The difference will be that the E-M1 achieves better sharpness at pixel level, at the risk of seeing some moiré patterns, while the GH4 will be somewhat duller at maximum magnification, with the risk of moiré being much small. This is a common priority with video oriented cameras.

Video


Looking at the sensor data sheet, we see that the camera is capable of 4K video recording at a maximum framerate of 30fps, and at 1080p with 60fps maximum. And this is the big news: The Lumix GH4 is the first mirrorless camera to support 4K video.

ResolutionFramerates
4096x2160 (17:9, 1.85, Cinema 4K)24p
3840x2160 (16:9)24p, 25p, 30p
1920x1080 (16:9)24p, 25p, 30p, 50p, 60p
1280x720 (16:9)24p, 25p, 30p
640x480 (4:3)25p, 30p

There is a drawback with 4K video, though, the camera only uses parts of the sensor at this resolution, as illustrated below:


As the Lumix GH4 does not have the multi aspect ratio sensor, just like the Lumix GH3, there is a crop factor when switching from photos (4:3) to 1080p video (16:9). The sensor diagonal is 8% shorter in 16:9 than 4:3, meaning that there is an additional crop factor of 1+8% = 1.08. So in 1080p video, a 14mm lens behaves like a 15mm lens in terms of the diagonal field of view. This is just like the Lumix GH3.

With the Lumix GH4 in 4K video mode, though, the crop factor is much larger. In 4K mode, multiply the focal length with 1.31, and in Cinema 4K mode, use 1.24. So the 14mm lens becomes equivalent to 18mm and 17mm, respectively. See the table below:

ResolutionSensor area usedDiagonalCrop factor
Photos (4:3)4608x345657601
1920x1080 (16:9, Full HD)4608x259252871.08
4096x2160 (17:9, 1.85, Cinema 4K)4096x216046311.24
3840x2160 (16:9, 4K)3860x216044061.31
1920x1080 (16:9, Full HD, ETC mode)1920x108022032.6

So all your lenses become "more narrow" when using the 4K feature. The reason for using only a part of the sensor area for 4K video is processing power: If the camera would use the whole sensor area and then scale it down to around 4000 pixels horizontally for each frame, this would require far too much processing. A high quality rescale, to avoid artefacts, requires a lot of CPU resources.

Another welcome news, is that the Lumix GH4 is the first Panasonic Micro Four Thirds camera to be multi region, in the sense that it can record both 25p and 50p (PAL region) and 30p and 60p (NTSC region) using the same unit. The camera requires a reboot when switching region.

This means that you can choose between using 50p or 60p (for full HD video capture), and between 25p and 30p for 4K video capture. Previously, you were only able to use one of them, depending on where you bought the camera in the first place.

Normally, you would want to use the "correct" setting for your own location. For example, if you are in a PAL region, and use 30p, you could risk getting an interference between the video framerate and the frequency of artificial light, causing an annoying flickering. Here is a demonstration of how this might look like. However, having the choice between 25p and 30p is very good.

There are other improvements as well. For example, the GH4 features a zebra pattern to warn against overexposure during video recording, and also implements focus peaking. See focus peaking demonstrated with the Sony NEX-3N.

Photos


The Lumix GH4 improvements are not limited to video, far from it. The GH4 improves a lot of the photographic features as well. The flash sync speed is improved from 1/160s to 1/250s. And the maximum shutter speed is raised from 1/4000s to 1/8000s.

Further, the GH4 is capable of taking 12 still images per second, up from 6 with the GH3. And the GH4 can take 7 frames per second with focus tracking enabled, which should be useful for sports photographers.

Electronic shutter


The GH3, and other Panasonic cameras like the G6 feature an electronic shutter mode. This is useful, since it is completely silent, and does not cause any shutter shock. However, as the electronic shutter reads the image data sequentially at a very slow pace this mode is not so useful.

Looking at the sensor data sheet again, we can see that it is capable of a full scan in 1/14.7s. This is about 50% faster than the Lumix GH3. Hence, the electronic shutter mode should improve, but you still face a big risk of rolling shutter artefacts.

The Nikon 1 cameras are largely based on an electronic shutter, and are capable of a full scan in 1/80s, eliminating the risk of rolling shutter. I wish Panasonic would implement a fast scanning electronic shutter as well.

Availability and price


Panasonic have announced that the Lumix GH4 will be available in May. The price is USD 1700 and GBP 1300, which is a quite fair pricing.

If you are interested in the Lumix GH3, can you expect the price to drop soon? I don't think so. When the GH3 was introduced, the GH2 kept selling alongside at the same old price, until they were out of stock. There was no GH2 fire sale in my market. I would expect the GH3 to continue selling at a fairly constant price this spring. So if you are interested in the Lumix GH3, don't wait for the price to drop dramatically this spring.

The competition


Here's the thing: Not many cameras feature 4K video yet. If you want an interchangeable lens camera with 4K video, the only choice is the Canon EOS 1D C, which is a rather large DSLR camera. There are also the professional RED digital video cameras, but they are out of the scope for the consumer market.

Blackmagic say they have a 4K video camera in the works, however, it has been delayed a lot. In the mean time, they have the Cinema Camera capable of 2.5K video at a high dynamic range.

About a year ago Nikon said that they would implement 4K video in their Nikon 1 range of mirrorless cameras. However, nothing of the sort has surfaced, and the Nikon 1 range does not appear to be doing well in the market.

Looking at the non-interchangeable lens market, there are some offerings: The Sony FDR-AX1 is large and expensive, but you can buy it now. There is also a less expensive Sony FDR-AX100 expected to ship in March. And from JVC, the GY-HMQ10. All of these have fairly small sensors, though, compared with the Lumix GH4.

CameraForm factorSensor sizeCrop factorMax FPSPriceAvailable
Sony A7sDSLRFull Frame1.130, needs external recorder$2.500September 2014
Canon EOS 1D CLarge DSLRAPS-H (4K mode)1.525$12.000Now
Blackmagic Production CameraCompact, tripod mounted Super 35mm1.530$3000February 2014
Lumix GH4Small DSLRFour Thirds2.5 (4K mode)30$1700May 2014
Sony FDR-AX100Small Camcorder1''330$2000March 2014
Sony FDR-AX1Camcorder1/2.3''5.260$4500Now
JVC GY-HMQ10Camcorder1/2.3''5.260$5000Now
GoPro Hero 3+ Black edAction camera1/2.5''5.715$400Now

Shortly after Panasonic announced the Lumix GH4, Blackmagic said it would ship it's "Production Camera", which is 4K capable. It is going to be sold at USD 3000, 25% less than originally announced. It has a Canon EF mount capable of electronic aperture control. Compared with the GH4, you get a slightly larger sensor, but a much less ergonomic camera body. It essentially must be tripod mounted. You also lose the autofocus, compared with the GH4.

The Sony FDR-AX100 is probably the closest competitor to the Lumix GH4, with a similar price, and a slightly smaller sensor. It comes with a non-interchangeable lens, though, and cannot use the host of Micro Four Thirds and legacy lenses that you can mount on the GH4. Choosing between the Sony FDR-AX100 and the GH4 comes down to what type of camera body you want, and whether you want to be able to change lenses or not.

The Sony A7s was announced in April 2014, and offers 4K video from a Full Frame sensor, almost without any cropping. You lose some pixels on either side, bringing the crop factor to approx 1.1. The downside is that it does not record 4K video internally, you need an external HDMI recorder, like the Atomos Shogun, priced at around US$2000, to be available around the end of 2014.

One of the reasons why Sony used a 12MP sensor on the Sony A7s is just this: To be able to do 4K video with very little cropping. Had they used their 24MP sensor, they would have needed to record 4K video off the centre 8MP portion of the sensor, or to sample the 4K video from individual pixels in a grid off the sensor surface.

Cropping has negative side effects, of course, and the sampling can lead to line skipping artefacts. A quality down scaling from a larger resolution sensor to 4K video is very computer intensive, and cannot be done in real time by any consumer camera with todays technology level. That is one of the reasons why they chose a low resolution 12MP sensor for the Sony A7s.

Conclusion


With the Lumix GH4, Panasonic are the first movers. The first mirrorless camera to feature 4K video. I expect this to attract a lot of attention. There are a lot of amateur enthusiast who would like to try 4K video, and are willing to pay the premium price for the GH4.

I would say that Micro Four Thirds is better suited for video than the Canon EOS 1D X. The shorter register distance makes it easy to use legacy lenses with a number of adapters. And a lot of people like using legacy lenses for video.

I anticipate that the GH4 will draw a lot of people to the Micro Four Thirds camp. It is a game changer for Panasonic.



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