GH5 e-shutter is slower!

The Lumix GH3 introduced a new concept in 2012: Electronic shutter. Meaning that you no longer had to rely on a mechanical curtain shutter in front of the sensor to start and stop the exposure, this could now be done purely electronically by the sensor itself.

The benefits are obvious: Less wear on the shutter if you want to make a time-lapse, for example. And a perfectly silent camera.

However, there was also a big downside: The sensor was scanned vertically during electronic shutter usage, and this scan was slow, taking a total of 1/10s. If you moved the camera, or the subject moved in this time, you would get skewed lines and weird effects. And can you hold the camera steady for 1/10s? No, that is impossible.

So the usefulness was rather limited. Future implementations increased the e-shutter scan speed, however, at the expense of the bit depth. Using only 10 bits rather than 12 bits normally, that would increase the scanning speed, but reduce the dynamic range capabilities. This was done, e.g., in the Lumix GH4, angering some users. And the scan speed was still quite slow, way slower than cameras from the Nikon 1 series, for example, with a 1/80s scan speed.

With this backdrop, the big question is: What about the Lumix GH5? What is the electronic shutter scanning speed and bit depth? Does it finally make the electronic shutter useful? That is what I will answer here, by comparing with two similar cameras:

Back: Lumix GH5 (left) and Lumix GH4 (right), and Lumix G85 in the front. Despite these cameras appearing to be the same size, they are in fact significantly different, with the GH5 being largest, and the G85 being smallest.

Speed of E-shutter readout

The Lumix GH3 electronic shutter had a readout speed of 1/10s, which is very slow. This leads to significant rolling shutter artifacts, that you can read about here. How do the cameras above compare?

One way to test the speed of the electronic shutter is to take a photo at a fast shutter speed in artificial light. For about a century or so, people have been using incandescent light bulbs for electronic indoor lightning. Even when used on alternating current (AC), the light is stable. Since the filament is heated, it emits light also when the alternating current is at zero.

However, traditional incandescent light bulbs are now being replaced with the energy saving fluorescent light bulbs. They tend to flicker at 100Hz (in Europe) or at 120Hz (in the US). The lights don't flicker at 50Hz and 60Hz, as you might expect. This is since during each period, the electrical current reaches two peaks, see the illustration below:



Here are images taken at ISO 3200, 1/400s with the three cameras:

Lumix GH5	Lumix GH4	Lumix G85

Each yellow row represents 1/100s of scan time, and the more rows, the slower. So there is your answer, the Lumix GH5 has the slowest e-shutter scan speed of the three. Who would have guessed?

By counting the lines more thoroughly, I get these approximate scan speeds:

Lumix GH5	Lumix GH4	Lumix G85
1/22s (but approx 1/50s at ISO 800 or lower)	1/30s	1/25s

Bit depth

Having answered the first question, what about the second? Do you lose some bit depth, and, hence, dynamic range, when using the electronic shutter?

To find out, I took the same picture using the three cameras, and I underexposed by two stops. Then I increased the exposure by three stops in a RAW editing program. That reveals how much details are left in the shadows. I used ISO 200, the base ISO, in all the cases.

Here are the pictures, after adjusting the exposure by +3 in post processing, using the RAW file:

	Lumix GH5	Lumix GH4	Lumix G85
Mechanical shutter
Electronic shutter

They look quite similar on first look, but some crops at 100% reveals the difference. The top crops are from the mechanical shutter, while the lower are from the electronic shutter:

What we see here is that the Lumix GH5 has the same image quality using both the mechanical and electronic shutters. The other cameras, on the other hand, lose some details in the shadows in electronic shutter mode, indicating a lower bit depth.

So the Lumix GH5 prioritizes image quality over scan speed, which is why it is the slowest in my above test. Also, it has a higher resolution at 20MP, which slows down the sensor scan.

Keep in mind that these images were underexposed significantly, and then raised in post processing. So the image quality you see here is much worse than what you would get with normal use. In real life use, you would probably not see any difference at all between the electronic shutter and mechanical shutter images, using the Lumix GH4 or G85.

Also, when using a higher ISO, the lower bits are probably mostly noise anyway, meaning that there is little to benefit from the extra bits in the GH5 rendering.

Conclusion

The Lumix GH5 prioritizes image quality over scanning speed in electronic shutter mode. While this will make many fans happy, there is a downside: A slower sensor scan which leads to rolling shutter effects.

Here are some examples taken using the electronic shutter with the GH5. In the first, I pan the camera following the bird, which skews the building in the background:

In the second, a passing car is skewed, due to the speed:

The shutter speed is not relevant for these effects. Even if you set a very fast shutter speed, you would still get the skewing. It is the scan speed which creates these effects, and it cannot be changed. The only solution is to use the mechanical shutter.

But there is good news! If you use the 6K photo mode, then the camera is able to scan the sensor surface much faster, which should help avoiding the rolling shutter effects. It probably caps some bit depth, but as you don't get any RAW file anyway, I guess it doesn't matter much.

Here is the Joker picture taken with 6K photo mode, indicating a scan speed of 1/60s, quite impressive:

	Lumix GH5	Lumix GH4	Lumix G85
Electronic shutter scan speed	1/22s (1/50s at ISO 800 and lower)	1/30s	1/25s
Electronic shutter bit depth	12	10	10
6K Photo scan speed	1/60s	NA	NA
6K Photo bit depth	10?	NA	NA

So my conclusion is: If you want to use the electronic shutter and get the best image quality, make sure to keep your camera stable and use the ordinary electronic shutter mode.

If you are going to do actions shots, use the 6K photo mode, which does the same, but with a faster scanning, and without the RAW file output.

The really positive news here is that with the Lumix GH5, Panasonic gives us this choice.

	Electronic shutter	6K Photo
Pros	Best image quality	Less rolling shutter effects, better for sports, animals, etc
Cons	Can give skewed effects due to rolling shutter	No RAW output, however, the JPEG image is actually quite good. Be sure to get the exposure and white balance correct when taking the images

Out of the three cameras, I would recommend the Lumix GH5 if you can justify the investment, otherwise, get the Lumix G85. The Lumix GH4 is good for those who must have the V-Log functionality, but want the cheaper option.

Olympus E-M5 II shutters

The Olympus E-M5 Mark II introduces a number of firsts in Micro Four Thirds: In-body image stabilization usable for video recording (tested here), high resolution mode (tested here), and the first Olympus camera with an electronic shutter mode. In this article, I will compare the shutter modes of the Olympus E-M5 Mark II.

Electronic shutter mode was introduced with the Lumix G5 camera in 2012. The same Lumix G6 and Lumix GH3 shared the same electronic shutter implementation, which has a significant drawback: The sensor is read during a rather slow period of 1/10s second, which can lead to significant rolling shutter effects.

The Lumix GH4 (my review) improves upon this with a 1/30s sensor output, on the other hand, it only uses 10 bits depth in electronic shutter mode, which can give you less effective dynamic range.

GH4 shutters

Recently, an interesting Panasonic sensor data sheet popped up. It is believed to describe the sensor sitting in, e.g., the Lumix GX7 and GM1.

The data sheet says that there are two options for electronic shutter readout: 12 bits in 1/15s and 10 bits in 1/22.5s. It has been demonstrated that the Lumix GX7 has a readout speed of 1/15s, and I have measured the speed of the electronic shutter in the GM1 to around 1/25s.

I also saw that the GM1 had slightly less details in the shadows at ISO 200 when using the electronic shutter. This is because it only uses a 10 bit readout with the electronic shutter.

Worse image quality with the E-shutter?

So, does the same apply to the Lumix GH4?

GH3 electronic shutter

I've written about the electronic shutter feature of the Panasonic GH3 before, concluding that the feature is very useful, but has some side effects. The electronic shutter is useful since it is totally silent, and vibration free. However, the electronic shutter reads the image sequentially, row for row, rather slowly, taking about 1/10 second in total. If you move the camera during this time, you get odd wobbly effects, even with a very fast shutter speed. This is a rolling shutter artefact.

To illustrate this, I have superimposed two exposures in an animated GIF. They were taken with the Lumix G 14mm f/2.5 at f/4, 1/60s, ISO 200. Normally, one would think that 1/60 second is safe for handholding a shot with a wide angle lens, however, since each full exposure takes 1/10 second, any movement during the exposure will result in a skewed image:



Looking at only one of the two exposures above, one might not notice any problems. However, when seeing both, it is clear that at least one of them, probably both, are not geometrically correct. So, is this a problem? When holding the camera reasonably still during the exposure, and not photographing very square objects, it is no issue. If you critically need rectilinear images, then you are better off using the normal mechanical shutter.

GH3 rolling shutter examples

The Panasonic GH3 has a very useful feature, the electronic shutter. One disadvantage of the function is that it suffers from quite severe rolling shutter artefacts. Read more about it here.

Here are some example images, taken with the electronic shutter, the mechanical shutter, and a still image from the video output:

Electronic shutter (f/1.7, 1/250s, ISO 200):

Mechanical shutter (f/1.7, 1/250s, ISO 200):

Video still image:

We see that the electronic shutter has a slower sequential readout than the video mode. This is unlike the Panasonic GH2, which used the video output for the electronic shutter mode, and they shared the same rolling shutter properties. But then again, you only got a 4MP image with the GH2 electronic shutter mode, and it was quite unsharp, probably scaled up from 1080 lines or thereabouts.

This will be my last Panasonic GH3 related article for a while, and the review I am writing will be delayed. The reason is that I have delivered the camera for a warranty repair: The automatic switching between the LCD and EVF suddenly stopped working.

My GH1 and GH2 have operated flawlessly for years. It is perhaps ironic that the GH3 was my first Panasonic camera to require a repair, since it is marketed as being extra solid and weather proof.

The last time I had a Panasonic item for repair, due to uneven aperture diaphragm blades, they kept the lens for three months. And when I did hear from them, they just gave me a brand new lens, which turned out to exhibit exactly the same problem.

I'm hoping they don't keep my GH3 for as long.

GH3 electronic shutter

One of the interesting new features of the Panasonic GH3 (my review) is the possibility to use an electronic shutter. It's not correct to say that this is a new feature, though, as the Panasonic G5, launched some months earlier, also has an electronic shutter. Probably, these cameras share some sensor components.

The electronic shutter has the advantage of being silent, of course, since no mechanical shutter is moving at all. It probably also has a quicker response time, however, I have not tested if this is actually a fact.

On the downside, the electronic shutter suffers from heavy rolling shutter artefacts, making it virtually unusable with moving subjects, or with a long lens. It also does not work with a flash, and cannot be used with high ISO or a very slow shutter speed. I'll get back to all of this in the article.