The Panasonic GH3 is widely regarded as a great compact system camera for shooting video, but its reputation for stills photography is a little more lacklustre. Despite the fact that its headline specification is its ability to shoot 4K video, Panasonic is hoping that the GH4 will gain greater respect for its stills capability.

The company has clearly invested a lot of time and effort in improving on the GH3 for the GH4, and the new camera has an extensive list of new or enhanced features. However, some may be surprised to learn that the sensor's pixel count has stayed the same, 16.05 million, even though the sensor is completely new.

Features

As a Micro Four Thirds (MFT) camera, the GH4 is compatible with a wide range of optics from Panasonic and Olympus, as well as a handful from Sigma, Tokina and Voigtlander.

Because the sensor is smaller than full-frame, there's a 2x focal length multiplication factor. As a result, the Panasonic Lumix G X Vario 12-35mm f/2.8 Asph lens, for example, has a focal length range equivalent to a 24-70mm optic on a 35mm camera when shooting stills.

Panasonic GH4
Micro Four Thirds lenses are compatible

As it sits at the top of Panasonic's camera line-up, the GH4 is aimed at experienced photographers and, naturally, it has the usual program, aperture priority, shutter priority and manual exposure modes. However, there's also a collection of modes to help less experienced photographers, including Panasonic's Intelligent Auto (iA) mode.

Panasonic has coupled the new 16.05-million-pixel Digital Live MOS sensor with the Venus Engine IX. This is a new processing engine, as the Panasonic GX7 has the Venus Engine VIII and the GH3 has the VII version.

Recording 4K video is very demanding on processing power, and consequently the Venus Engine IX is a quad-core processor. In addition, the sensor has twice the readout speed of the GH3, reaching 200Mbs.

According to Panasonic's Michiharu Uematsu, this sensor and processor combination enables the GH4 to produce very slightly better quality images than the GX7, which was previously claimed to produce the best quality images of any G-series camera.

Clearly the company is confident of the GH4's noise control, as sensitivity may be set in the native range of ISO 200-25,600, with ISO 100 as an expansion setting. In comparison the GH3 has a range of ISO200-12800, with ISO125 and ISO 12,800-25,600 being available as expansion settings.

Panasonic GH4
ISO has its own button

In single-AF mode the GH4 can shoot continuously at up to 12 fps (frames per second) with a UHS-III SD format card installed. This rate drops to 7.5fps in continuous autofocus mode. Panasonic will introduce a UHS-III card when the GH4 comes to market.

One of the challenges for compact system camera manufacturers has been to improve the speed of their autofocusing, because they use the traditionally slower contrast detection system. Panasonic has introduced a new approach for the GH4, which uses its novel DFD Technology. This system looks at the contrast of the scene at two different defocused points to help it calculate the correct focus point more quickly. Panasonic claims that this enables the GH4 to achieve a focus time of 0.07 sec whereas the GH3 achieved 0.09 sec.

The faster processing engine, quicker sensor read-out and cleaner signal should enable the camera to focus its lens in poorer light, and Uematsu says that the GH4 can focus down to -4EV. Uematsu is also keen to emphasise that all the improvements required to allow 4K recording have a positive knock-on effect for still images.

In addition, the camera has a 49-area AF system that allows the user to customise which areas are used. It's even possible to select two separate areas or groups of areas.

Focus peaking was high on the list of demands for the GH3, but it never arrived in a firmware update. Happily, the GH4 has focus peaking (and zebras) to help with manual focusing and video recording by highlighting the areas of highest contrast. This is accompanied by the picture-in-picture view first seen with the GX7 to allow the whole scene to be seen while an enlarged view is visible.

Panasonic GH4
The three-inch screen articulates

Panasonic has improved both the electronic viewfinder and the three-inch vari-angle screen since the GH3, giving the two devices in the GH4 higher resolutions of 2,360,000-dots and 1,040,000-dots respectively. As before, both are OLED units and the main screen is touch-sensitive.

The GH4 is capable shooting video at a range of resolutions, including Full HD, in addition to 4K, and there are options to shoot in MOV, MP4, AVCHD Progressive formats at a range of frame rates.

To maintain the best image possible Panasonic crops the GH4's image to create the 4K rectangle. As a result the focal length of the lens effectively lengthens by approximately 17%.

Cropping the image produces better quality footage than using zooming or interpolation technology. Those who want the very best video quality, however, will need to invest in the optional Interface Unit that bolts onto the bottom of the camera. This enables clean, uncompressed 4K footage to be recorded to an external device. It also has two XLR microphone ports, a phantom power supply for mics and four SD video-out sockets. This unit also adds audio monitoring and control capability, as well as the ability to use an external timecode to synchronise several cameras.

Panasonic will distribute the GH4's Interface Unit through its professional video and channel, as it will appeal to professional videographers who plan to use the GH4 as part of a rig with an external monitor and recording facility etc.

Like the GH3, the GH4 has Wi-Fi connectivity built in, but this is joined by an NFC chip to enable quick connection to other NFC devices such as Android phones and tablets. As before, the GH4 can be controlled remotely using Panasonic's free smartphone app via a Wi-Fi connection.

Build and handling

There are only a few noticeable differences in the appearance of the GH4 in comparison with the GH3, they are very closely matched in size and weight and have an identical control layout.

The eye-cup around the electronic viewfinder (EVF) is slightly larger on the GH4 to offer a little more shade from strong sunlight, for example. There's also a lock button at the centre of the mode dial to prevent it from being knocked out of position.

Panasonic GH4
The viewfinder's eye-cup has been enlarged

There's also a second self-timer option on the drive mode dial on the top-plate of the camera.

As before, the GH4 has a magnesium alloy body that is dust- and splash-proof. It has the same solid feel as the camera it replaces and its new speckled surface finish looks a little more serious.

Panasonic has also bolstered the GH4's durability by giving its shutter a life-span of 200,000 cycles, double that of the GH3.

I used a pre-production sample GH4 indoors and in pretty low light, but the EVF gave a nice clear view with plenty of detail with no speckling or noise being visible. The OLED screen on the back of the camera also displayed a clear image. I will have to wait for a full-production sample before I can see how this performs in bright light, but I can confirm that the screen is very responsive to the touch.

Performance

Our tests confirmed Panasonic's claim that the GX7 produced the best image quality of any of its digital cameras at the time of its launch to be valid. We are now looking forward to investigating the company's claim that the GH4 produces better quality images than the GX7.

The test sample prints that I was shown before the camera's announcement also indicate that the camera is capable of holding its own against competing cameras, including some full-frame models – at least in some situations.

In the past, Panasonic's cameras have been found wanting a little in comparison with the competition in low light conditions, and naturally the company has been working on this area. The challenge is to keep noise to a minimum while preserving detail. Panasonic's recent cameras have had much better noise control, with less of the bold red speckling being visible in shadows. It will be interesting to see what further steps have been made with the GH4's new sensor and processor combination when we get a production sample in for testing.

I'm also keen to see how the AF system performs in a range of conditions. I found that the GX7 is capable of getting moving subjects sharp in good light provided that the active AF point is over the target, but it falters in low light. I'm hoping that the GH4's system proves a little more capable in this respect.

Panasonic's metering and white balance systems have been found to be good performers in the past, producing well-exposed, natural-looking images. However, the GH3's automatic white balance setting sometimes produced rather cool looking images in warm sunlight. This was dealt with very easily by switching to the Sunny white balance setting. We will investigate this with the GH4.

Early verdict

Panasonic has not announced the price or the availability date of the GH4 and its Interface Unit, but we can assume that the new camera will retail for a figure that's reasonably comparable with the list price of the GH3 (US$1,299.99/£1,549/around AU$1,230).

Although Panasonic may want to promote the GH4 as a stills camera, the fact that it is the first compact system camera to record 4K video is going to make it grab the attention of keen videographers. The company has also boosted the camera's video capability with focus peaking and zebras. Plus there's the Interface Unit to allow serious and professional video shooters to build a professional rig around the camera for a fraction of the usual cost.

It will be very interesting to see what steps forward have been made with image quality. The fact that the company has stuck with the same pixel count on its sensor means that it is unlikely that there will be significant strides made with detail resolution at the lower sensitivity settings, but better noise control could enable more detail to be visible at higher settings.

It's interesting to note that while the Nikon D800 was greeted with great enthusiasm, not least because of its 36Mp sensor, and there are numerous cameras available with 18-24Mp sensors, 16Mp sensors are still widely accepted. The Nikon Df is a particular case in point. However, the Df is a full-frame sensor (36x23.9mm) that allows the pixels to be large (comparatively), whereas the Four Thirds sensor in the GH4 is smaller than APS-C format at 17.3x13mm, so 16Mp is pushing its capability further.

There are significant benefits to having a smaller sensor, the smaller size of the camera lenses being the most obvious. There's also the opportunity to have better image quality across the whole frame because (with the right design) the sensor can cover the lens's image circle more easily. However, a small sensor limits the potential size of the pixels and this gives Panasonic a challenge when it comes to controlling noise. That said, Olympus faces exactly the same challenge and has pulled it off in its recent Micro Four Thirds cameras (thanks in part to Sony's sensors) - so perhaps Panasonic can do the same.

The GH4's low-light autofocus capability is another important area that I'm looking forward to testing. At the moment cameras such as the Panasonic GX7 and Olympus OM-D E-M1 can hold their own against many SLRs in good light, but they can't compete so well when focusing automatically in low light conditions. Perhaps this will change with the GH4.