Panasonic Lumix DMC-GH4 Review

Performance starts with image quality, which is the criteria used as the foundation of our digital camera ratings. Ergonomic issues may get in the way, but in the end, image quality counts the most. For an ILC, image quality greatly depends on the lens used. While color, noise, exposure and dynamic-range are properties of a camera, distortion, vignetting and chromatic aberrations are properties of the lens. Sharpness and contrast depend on the weakest link. That is, a camera cannot capture more details than a lens lets through. Conversely, it is quite possible for a lens to transmit more details than a sensor can capture.

Image Noise & Details

The Panasonic Lumix DMC-GH4 turns in an impressive performance when it comes to image noise. Without a doubt, this is the best output seen to date from a Panasonic camera. Images remain noise-free until ISO 800 and miniscule speckles of noise appear at ISO 1600, just enough to be detected without affecting the maximum print size. With its 16 megapixels, it can produce sharp and crisp 20" x 15" prints.

There is a slight amount of visible noise at ISO 3200 which stills allows for nice large prints. ISO 6400 shows a little more noise, reducing the maximum print size by a few inches, yet remaining usable for mid-sized prints. By ISO 12800, fine details get destroyed by image-noise. Mid-sized prints are sill possible which is a good performance for a modern digital camera. ISO 25600 is considerably more noisy which even shown in small prints. Such prints are usable in an emergency though, producing a recognizable subject with decent contrast.

Noise-reduction is adjustable ±5 along an arbitrary scale, where the default setting of 0 is damaging to details at all sensitivities. The best results are obtained at -2 which shows little difference in image-noise at low ISOs. From ISO 800 onwards, higher NR settings can hide noise but they do even more damage to image details.

Sharpness is adjustable on a ±5 scale as well. The default of 0 is visibly soft and lower levels are unusable. Higher levels get progressively sharper with +1 giving sharp images with virtually no sharpening artifacts.

Color & White Balance

Color accuracy is generally good. The Natural Photo Style produces the most realistic colors with a slight mix of over and under-saturation depending on the hue. Accuracy improves slightly be reducing both Saturation and Hue to -1. Otherwise, one should be able to obtain highly accurate colors by shooting RAW.

Without being perfect yet, Automatic White-Balance has improved compared to the GH3. While it is capable of nailing WB under all sorts of conditions, this mirrorless camera produces slightly inconsistent results indoors and outdoors. The Custom WB option fairs much better with generally neutral results. Even that can be fine-tuned in 19 steps along 2 axis for greater flexibility.

Exposure & Dynamic-Range

The multi-segment metering system of the Panasonic GH4 is quite good. It is not entirely conservative and will often blow small highlights. This is a more consumer-oriented approach but requires negative EC from time-to-time to avoid clipping. Since it is tuned to produce bright images, positive EC is rarely needed.

Dynamic-range of the GH4 is comparable to the best Micro Four-Thirds cameras. This puts it one-to-two stops behind cameras with APS-Cs. This is a matter of physics since an equal resolution APS-C sensor must have larger photosites than a Four-Thirds one. Still, the GH4 is capable of capturing scenes having a wide dynamic-range.

The GH4 offers more control over the tone-curve than any Panasonic before it. The default overall contrast is a little high and reducing it by one step allows images to retain more details. Further changes only shift tonalities around, not adding much to what is captured.

Auto Focus

The GH4 keeps the ultra-fast Contrast-Detect AF system of the GH3 and makes it even more sensitive, down to a class-leading -4 EV. It locks focus quickly and accurately under most circumstances. This mirrorless rarely takes more than ½s to lock focus and, in good to moderate light, it takes closer to a ¼s. This excellent performance closely matches other top-of-the-line mirrorless cameras.

Optionally, just like on the GH3, the Eye-Start sensor can trigger autofocus before the shutter is pressed half-way. This brings the lens much closer to where it should be when its time to autofocus but quickly drains the battery, particularly when the camera is dangling from your neck and the Eye-Start sensor constantly detects proximity. Panasonic added a system to reduce premature focusing be measuring camera jitter. When jitter goes down, such as when a photographer is preparing to take a shot, the camera automatically triggers AF.

Speed

The Panasonic Lumix DMC-GH4 is very quick and responsive. The camera responds instantly to every dial-turn and button-press. The processor is very fast and delivers a performance which is must closer to that of a DSLR than most mirrorless digital cameras. Crucially, the EVF/LCD lag is finally imperceptible.

The GH4's performance is characterized by these measurements:

• Power-On: ¾ second. Good.
• Power-On to First-Shot: 1¼s seconds. Good.
• Autofocus: ¼ - ½s. Closer to ¼ with Quick AF enabled and in good light. Excellent.
• Shutter-lag: Nearly instant with less than ½s blackout. Above average.
• Shot-to-shot: Just above 1/3s. Superb.
• Playback: ¼s to enter, ¾s to exit. Average.
• Power-Off: 1½ seconds. Good.

The autofocus speed and shutter-lag are clearly what is important which is where the GH4 does best. The shot-to-shot speed on this mirrorless is impressive. This is the one measurement which the GH4 does considerably better than its predecessor.

The 12 FPS continuous drive is equally impressive and, given that there is no noticeable display lag, the GH4 is the first Panasonic mirrorless to be suitable for action photography. Although the buffer-depth is quote at 100 JPEG images, the review unit managed a whopping 260 frames before slowing down!

The Panasonic Lumix DMC-GH4 is powered by a proprietary Lithium-Ion battery which provides 540 shots-per-charge according to the CIPA standard. This is significantly above average for a mirrorless camera.

The Panasonic GH4 offers the most sophisticated video feature-set of any digital camera to date, surpassing the GH3 by a significant margin. This narrows the gap between mirrorless cameras and camcorders in terms of video-centric features, plus mirrorless cameras still deliver superior video-quality due to their larger sensors. While the GH3 acquired general video features, the GH4 adds on professional capabilities too.

With its Cinema 4K capture, the Panasonic GH4 delivers the highest-resolution video of any mirrorless camera. Standard 4K is 4X the resolution of full 1080p which comes up to 3840x2160 and has exactly the same 16:9 aspect-ratio. This is called Ultra-HD and this Panasonic can record it at 30, 25 or 24 FPS. Cinema 4K is slightly wider at 4096x2160 which the GH4 can capture at 24 FPS exclusively.

At 1080p, the GH4 can record normal video progressively at 60 FPS. It can also record at up to 96 FPS for slow-motion. This requires a significant throughput from the processor but makes it possible to render motion more smoothly than most digital cameras. When space becomes an issue, lower-resolution 720p or VGA video can be captured at 30, 25 or 24 FPS.

The Panasonic Lumix DMC-GH4 offers the most video encodings to date: AVCHD, MPEG-4 and H.264, with the latter packaged into a Quicktime file. There two 2 variants of MPEG-4, a standard one and an LPCM version which delivers higher video quality by using more sophisticated compression. Additionally, 1080p is available in All-Intra or standard IPB forms. The former creates much larger files which are easier to edit because each frame is encoded independently.

Each codecs gives access to different video-quality options:

Frame-Rate Resolution	60 FPS	30 FPS	24 FPS
4096x2160			MPEG-4 (LPCM) 100 Mbps Quicktime H.264 100 Mbps
3840x2160		MPEG-4 (LPCM) 100 Mbps MPEG-4 100 Mbps Quicktime H.264 100 Mbps	MPEG-4 (LPCM) 100 Mbps MPEG-4 100 Mbps Quicktime H.264 100 Mbps
1920x1080	MPEG-4 (LPCM) 200 Mbps*All-Intra MPEG-4 (LPCM) 100 Mbps MPEG-4 (LPCM) 50 Mbps MPEG-4 20 Mbps Quicktime H.264 200 Mbps*All-Intra Quicktime H.264 100 Mbps Quicktime H.264 50 Mbps AVCHD 28 Mbps AVCHD 17 Mbps*Interlaced from progressive. AVCHD 24 Mbps*Interlaced from interlaced.	MPEG-4 (LPCM) 200 Mbps*All-Intra MPEG-4 (LPCM) 100 Mbps MPEG-4 (LPCM) 50 Mbps MPEG-4 20 Mbps Quicktime H.264 200 Mbps*All-Intra Quicktime H.264 100 Mbps Quicktime H.264 50 Mbps	MPEG-4 (LPCM) 200 Mbps*All-Intra MPEG-4 (LPCM) 100 Mbps MPEG-4 (LPCM) 50 Mbps Quicktime H.264 200 Mbps*All-Intra Quicktime H.264 100 Mbps Quicktime H.264 50 Mbps AVCHD 24 Mbps
1280x720		MPEG-4 10 Mbps
640x480		MPEG-4 4 Mbps

The bit-rate, measured in megabits-per-second runs from 4 to 200 Mbps. Higher numbers usually signify more details and larger files. One may notice some oddities about the rates in the above table. The same bit-rates for 4K and Cinema 4K are also available for 1080p. There is therefore the same amount of data, it is only organized differently! 4K allows for more resolution but that will lose out to color or motion when encoded at the same bit-rates.

An All-Intra option exists for 1080p but not 4K or Cinema 4K. Actually, a 200 Mbps IPB mode for 4K and Cinema 4K would probably have better quality, yet there is no such option, which is rather strange. The processor must be reaching one of its limits, as we can see that Cinema 4K is not available at 30 FPS, despite being only 6% larger than standard 4K.

One sees better quality at 24 FPS compared to 30 FPS and, even more so, compared to 60 FPS. If motion is not crucial, it is therefore better to choose a slower frame-rate and enjoy higher quality output. Due to the All-Intra encoding, 200 Mbps videos will rarely show higher-quality. Such videos will be easier to edit though because there is no intra-frame compression.

Video quality of the GH4 is exceptionally good. Motions are rendered very smoothly when shooting at 60 FPS, which makes panning and zooming much more pleasant to view. Fine details and colors are well captured with little compression artifacts. In the presence of fast motion, some artifacts become noticeable but less so than usual at high bit-rates.

There are full manual-controls for video capture. When left in automatic or semi-automatic mode, the Panasonic Lumix DMC-GH4 does an excellent job at adapting exposure to the changing scene. Gain is applied gradually which keeps sudden jumps to a minimum. One can clearly see on the display when video exposure is off.

Crucially for the GH4, it can start and stop video-capture instantly in Movie mode. There is no point using other modes since the preview does not show framing correctly anyway unless one sets up the camera to not show image framing correctly.

Focus can be single-shot, continuous or manual for filming. AF-C keeps up quite well with small movements. Still, there is a chance that the camera might focus on the wrong subject, so it is best to focus manually. Using one of Panasonic's HD lenses makes this possible to do so quietly enough. Note that with the focus-switch to AF-S, the camera still focuses continuously while filming unless that is disabled in the Video menu.

Audio capture is possible via a built-in stereo microphone or an external sound source. The built-in microphone can be adjusted in 20 steps and features an optional wind-filter. As audio is being picked up by the GH4, it can be played back on a headset connected via a mini-jack input. The playback audio can come directly or from the recorded audio track to account for clipping and compression.

This camera can output video directly at 1080p via a mini-HDMI port. It can do so with or without overlay, making it possible to capture video using an external device. The GH4 can also embed Time-Code into videos as they are recorded. The Time-Code can start anew for each video or run continuously.

The Panasonic Lumix DMC-GH4 is a worthy successor the the GH2
Panasonic Lumix DMC-GH2 which precedes it. Externally almost identical, the GH4 packs much more processing power which turns it into a faster camera and gives it the ability to capture 4K Ultra-HD video, the must-have-of-the-day. The reality as that very few people have the displays to see 4K, yet the 12 FPS continuous drive and nearly lag-less 2.4 MP EVF advance this camera much more.

The GH4 is very features-rich. Panasonic fit it with a considerable amount of functionality with a class-leading emphasis on video. It offers a choice of 4 codecs, including All-Intra encoding for 1080p, and clean HDMI output, up to 4K no less. This makes it particularly appealing to videographers which will certainly be pleased with full manual-controls for video, including adjustable audio levels, plus stereo mini-jack input and output.

Image quality from the GH4 is top-notch for its sensor-size. Image-noise is comparable to an entry-level DSLR while dynamic-range is just over one stop behind modern APS-C cameras. Metering, color and white-balance are good but not without fault. This mirrorless is very fast and it always remains responsive. The autofocus system is incredibly sensitive, down to -4 EV, which no other camera can match. It is also very fast and manages to lock quickly and reliable under most conditions.

The built-in EVF with Eye-Start Sensor is very crisp with good contrast and color. It gives access to all functionality and makes shooting video at eye-level possible. Too bad there is no way to make it Exposure-Priority outside of Manual mode. The LCD too is nice and has good visibility. The hinge though has some flex and is definitely the weak-point of this camera.

The Panasonic GH4 offers class-leading 4K video with the versatility of interchangeable lenses. This combination is only offered by a single other camera, the Sony Alpha A7S
Sony Alpha A7S which costs almost twice as much and has significantly fewer native lenses. The GH4 uniquely takes this and fits it into a relatively compact and complete Ultra-HD digital camera.