Panasonic Lumix DMC-GH4 Review
JPEG tone curves / dynamic range
By Rishi Sanyal
Our Dynamic Range measurement system involves shooting a calibrated Stouffer Step Wedge (13 stops total range) which is backlit using a daylight balanced lamp (95 CRI). A single shot of this produces a gray scale wedge from the camera's clipped white point down to black (example below). Each step of the scale is equivalent to 1/3 EV (a third of a stop), we select one step as 'middle gray' (defined as 50% luminance) and measure outwards to define the dynamic range. Hence there are 'two sides' to our results, the amount of shadow range (below middle gray) and the amount of highlight range (above middle gray).
To most people highlight range is the first thing they think about when talking about dynamic range, that is the amount of highlight detail above middle gray the camera can capture before it clips to white. Shadow range is more complicated; in our test the line on the graph stops as soon as the luminance value drops below our defined 'black point' (about 2% luminance) or the signal-to-noise ratio drops below a predefined value (where shadow detail would be swamped by noise), whichever comes first.
Note: this page features our new interactive dynamic range comparison widget. The wedges below the graph are created by our measurement system from the values read from the step wedge, the red lines indicate approximate shadow and highlight range (the dotted line indicating middle gray).
Our comparison chart shows the GH4's default tone curve to have a less of the familar S-curve we're used to seeing with default renderings of most cameras. While the tone curve has S-shape character for the darker tones, the lighter tones above middle grey take a slow approach to clipping. This results in lower contrast around middle grey, since lighter tones aren't brightened as much as they are with, say, the Sony A7S. The more linear approach to clipped whites has another consequence: highlight tones do not roll off to clipped white as its rivales. Thus, one might expect more harsh transitions to clipped white with the GH4.
The GH4 offers slightly brighter rendering of shadows compared to the Sony a7S, which pushes its clipping point in our tests further down the wedge. The combination of a near-linear approach to clipped white and brighter shadows means overall image contrast will be slightly less than what you'd expect from a default Sony JPEG rendering, and it's really a matter of taste whether or not this is desirable.
The GH4 uses the latest version of Panasonic's 'iDynamic' dynamic range compensation feature for coping with high contrast scenes. It's an 'active' system that can reduce exposure to capture more highlight tones, while boosting the shadows and mid-tones to give the correct image brightness. There are three levels of iDynamic, plus an Auto setting that attempts to use the most appropriate setting for the scene being captured.
The graphs below show the progressively increasing shadow and midtone boosts higher levels of iDynamic apply. Exposure is constant, as the camera did not choose to apply any exposure shift for our wedge scene. iDynamic High applies quite an aggressive shadow/midtone boost that is just shy of what the Sony a7S applies at its highest, Lv5, DRO setting.
It's worth mentioning that Panasonic's particular implementation here is almost midway between Sony's DRO (Dynamic Range Optimizer) and Nikon's ADL (Active D-Lighting) features. While Sony's DRO modes are inactive (no exposure adjustment), Nikon's ADL mode typically applies a pre-determined amount of negative exposure shift. Panasonic has chosen a middle way: the camera appears to make a scene-dependent decision on how much, if any, exposure shift to apply.
It's rather conservative in its approach - for high contrast scenes we typically noted 0 and -1/3 EV exposure shift for 'Low' and 'Standard' iDynamic settings, respectively, and -1/3 to -2/3 EV for the 'High' setting. Lower contrast scenes often, appropriately, showed no exposure shift at all. Given the GH4's reticence to apply large exposure shifts, you won't typically see drastic changes in highlight retention with progressively higher iDynamic modes. However, you can expect to see more balanced handling of high contrast scenes, as our real-world example shows below.
You'll note above that at higher settings, the camera reduces the exposure slightly to retain more highlights, while applying enough of a shadow/midtone boost to render these tones brighter than they'd have otherwise been. We've indicated the amount of exposure shift the camera chose to apply, if any. 'iDynamic' Auto chose a setting of Standard in the scene above, which is fairly reasonable.
DR modes with exposure compensation
Although the GH4's iDynamic modes are rather conservative in terms of how much exposure shift they apply to capture additional highlight detail in high contrast scenes, you can yourself manually combine more aggressive exposure reduction with iDynamic to achieve a more significant effect. Below we show you how much exposure shift you can apply, for any iDynamic setting, while still achieving the proper midtone brightness. You'll note that the highlight range gained can be so extensive (up to 1.3 EV) that the highlight cutoff falls off the right side of the chart. Despite our chart not having enough highlight range to show you where the highlight cutoff occurs, you can expect to gain back in highlights whatever negative exposure shift you apply - while still maintaining proper midtone brightness.
Below we demonstrate the real-world effect of manually combining exposure compensation with iDynamic. The results roughly follow what the graphs above lead us to expect - the tone curves used in iDynamic Low, Standard, and High provide enough shadow/midtone lifts to compensate for around -0.3 to -0.7*, -1, and -1.3 EV reductions in exposure, respectively. This means you can gain between 0.3 and 1.3 EV of highlight range using these modes, when you manually apply some exposure compensation or expose for the highlights in Manual mode.
*Note that even though our tests indicated that iDynamic Low should be combined with -0.7EV exposure shift, we chose to apply -0.3EV exposure shift for our real-world iDynamic Low example as we felt the city tones at the bottom half of the image were more well maintained.
Though Thunderbolt 4 remains at 40Gb/s, its minimum requirements include dual 4K monitor support, faster external drive speeds and more.
You can now use compatible Fujifilm cameras with video conferencing software on macOS hardware without the need of a dedicated capture card.
The Epson V600 remains one of the most popular flatbed film scanners on the market. Revisit our review of this affordable and (mostly) easy-to-use option and see how its output compares to local lab scans.
Canon's mirrorless EOS R5 comes with a ton of features and capability stemming from its design inside and out. Come along with us on a guided tour of Canon's new high-end, high-megapixel camera and check it out for yourself.
Announced alongside the EOS R5, the R6 offers a lot of the same technology but in a more affordable, slightly more enthusiast-focused model. Take a closer look.
Alongside the EOS R5 and R6, Canon has announced a brace of lenses, all in the short to long telephoto range. Filling out the 'long' end are one L-series zoom, and two innovative primes.
Alongside a trio of telephoto lenses, Canon also announced a new 85mm this week. The RF 85mm F2 Macro IS STM is a compact, affordable alternative to the pro-oriented 85mm F1.2L.
The EOS R5 has been a long time coming – we knew it had 8K and we knew it had an AF joystick. But now that's it's here, what is it really like to use? Find out in our initial review based on hands-on time with the camera.
The R6 doesn't promise quite such headline-grabbing specs as its big brother, but it still packs a punch, whether you shoot stills, video or both.
Think you've read everything there is to know about the new Canon cameras? Chris and Jordan share eight important things you may have missed from today's Canon EOS R5 and R6 announcements.
We've been shooting around with the new Canon EOS R6. Initial impressions of image quality are positive, and out-of-camera JPEGs appear similar to that of the gold award-winning Canon EOS-1D X III. Have a look for yourself.
Canon has officially released the long-awaited EOS R5, the company's top-end full-frame mirrorless camera. Featuring a new 45MP CMOS sensor, Dual Pixel AF II system, 8K video capture and 20 fps bursts, this is the RF-mount camera we've been waiting for.
Although the Canon EOS R6 doesn't have the 45MP sensor and 8K video capture of the higher-end R5, it's still an incredibly capable camera with specs that outshine similarly priced peers.
The Canon RF 100-500mm F4.5-7.1L IS USM is the company's first super-zoom lens for RF-mount. Despite a relatively slow aperture range, it's very versatile, offering five stops of stabilization, weather-sealing and compatibility with Canon's new teleconverters.
Canon's RF 85mm F2 Macro IS STM is an inexpensive telephoto prime lens with a minimum focus distance of just 0.35m (14") and a 0.5x magnification. When attached to the new R5 and R6, it offers a whopping eight stops of shake reduction.
Canon has announced a pair of super-telephoto fixed-aperture primes. The 600mm and 800mm use diffractive optics to keep their size and weight down. They'll also be compatible with new 1.4x and 2x RF teleconverters.
Canon has announced a new small-footprint inkjet photo printer, the imageProGraf Pro-300. it will produce prints up to 13 x 19" and it goes on sale later this month for $900. A new textured photo paper will also arrive in July.
The new compression standard is set to reduce video file sizes by half to save space and speed-up transmission, paving the way for more portable 8K footage.
Sony recently confirmed plans to launch a successor to the video-centric a7S II. We don't even know the name of the camera, but Jordan already has a feature wish list for the new 'a7S III' – and it doesn't include 8K.
The Profot B10 is the first studio flash system that can be used when shooting with an iPhone camera.
The Pixii camera is an interesting little rangefinder camera that features a 12MP APS-C sensor and lacks a rear LCD display, opting instead to pair with your mobile device, which can be used to view and transfer images.
Sirui is launching an Indiegogo campaign for a wide-angle answer to its existing 50mm F1.8 anamorphic lens. The 35mm APS-C lens will come in a Micro Four Thirds mount with adapters for other systems.
Sony has added a 12-24mm F2.8 to its top-shelf 'G Master' series of lenses. It's the widest constant F2.8 zoom currently offered for full-frame, with a hefty price tag to match: it will sell for $3000 when it ships in mid-August.
Take a look at the view from Sony's new ultra-wide F2.8 zoom – we paired it with the a7R IV for some initial shooting.
Canon's EOS-1D X Mark III is one of the best DSLRs ever made. With fast burst speeds, great video quality and impressive autofocus, the 1D X III is equal parts cinema rig and sports shooter. Find out how it fares against steep competition in our full review.
Nikon Rumors is reporting that Nikon will announce successors to its Z6 and Z7 camera systems by the end of the calendar year.
Canon says the event, set to take place at 14:00 CEST in two days on July 9, will be its 'biggest product launch yet.'
The Verge Video Director, Becca Farsace, shows how she built a custom Raspberry Pi camera with effectively zero coding knowledge over the course of just three days.
The EOS R5 has been in the works for some time, and Canon has published a handful of specifications, but there's still plenty we don't know. What are you hoping to see from Canon's forthcoming flagship camera?
Canon's CE-SAT-IB satellite camera was destroyed alongside six other satellites during Rocket Lab's ironically-named 'Pics or It Didn't Happen Mission.'