Monday, 6 April 2015

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.


These are the shutter modes available on the Olympus E-M5 Mark II:

Normal mechanical shutter
This is the usual shutter mode, which has been implemented on all Micro Four Thirds cameras so far: The exposure starts with closing the curtain shutter completely, then opening it again for the start of the sensor exposure, and closing again after the desired shutter speed. Finally, the mechanical shutter opens again for live view.
Electronic first curtain shutter (anti-shock)
Compared with the normal mechanical shutter mode, this setting gets rid of the first curtain cycle, hence the name "electronic first curtain shutter". This avoids the shutter-shock associated with the first mechanical curtain closing, which is why it is often referred to as the "anti-shock" mode. This mode does not work for shutter speeds faster than 1/320s.
Fully electronic shutter (silent shutter)
In this mode, there is no mechanical shutter travelling at all, and hence, the shutter is completely silent. You may still get some noise, due to the lens focusing, or due to the lens aperture closing down upon the exposure.

Here is a high speed recording of the two variants of the mechanical shutter. The video recording was done using the Nikon 1 V3, which can record videos at 1200 frames per second.



We see that when starting and stopping the exposure, the shutter opens and closes during three frames, meaning that it takes around 3/1200s, or 1/400s. This is sufficient for the flash sync speed of 1/250s.

Bit depth


To speed up the electronic shutter readout, some Micro Four Thirds cameras reduce the sensor output from 12 bits to 10 bits. This reduces the dynamic range. Is this also going on with the E-M5 Mark II?

To test this, I have taken the same picture using the Olympus E-M5 Mark II, Lumix GH4, all using both the mechanical and electronic shutter modes. The photos were underexposed by two stops, to make the rendering of the shadows more challenging.

All the pictures were taken at ISO 200, the base ISO for these cameras:

Mechanical shutter
Electronic first curtain shutter
Electronic shutter
Olympus E-M5 Mark II

Lumix GH4

Looking at the JPEG output images above, there is little difference to find, beyond some unintended differences in the exposure. However, when I process the RAW files in Silkypix, increasing the brightness by three stops, I find some difference in the shadows:


What we see here is that the Lumix GH4 image quality is pretty much reduced when using the electronic shutter. You lose some effective dynamic range when using the electronic shutter mode of the GH4, compared with the mechanical shutter. There is more noise in the shadow areas.

This is because the GH4 is designed to use a 10 bit output in electronic shutter mode, to speed up the sensor readout, rather than 12 bits with the normal shutter. Less bit depth effectively means less dynamic range, and more noise in the shadow areas.

The Olympus E-M5 Mark II, on the other hand, appears to use the same sensor readout in both mechanical and electronic shutter mode. So you don't need to worry about losing the dynamic range when using the electronic shutter.

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 does the Olympus E-M5 Mark II 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 both cameras:


These results are quite easy to explain. With the Lumix GH4, I get about 3.3 stripes horizontally. Each stripe corresponds to 1/100s, hence, the total exposure takes about 1/30s.

The Olympus E-M5 Mark II has a slightly slower electronic shutter. There are about four stripes in the image, which means that the exposure takes 1/20s.

The slow electronic shutter means that you need to be careful when photographing moving objects, or when using a long lens without a tripod. But this effect is not only a problem, you can use it creatively too. Here are a couple of "cute" example images taken using the electronic shutter mode on the Olympus E-M5 Mark II:

Skewed cars moving at speed. Hold the camera upside down to make them lean the other way. Sigma 60mm, f/2.8, ISO 200, 1/1250s:


Bass string appears to move in a wave pattern, due to the rolling shutter effect. Sigma 60mm, f/2.8, ISO 800, 1/800s:


These two pictures would be impossible to take using the normal mechanical shutter.

Conclusion


The Olympus E-M5 Mark II introduces the very useful fully electronic shutter mode to Olympus cameras. This allows you to take truly silent pictures, and avoids shutter-shock.

On the other hand, the exposure goes over 1/20s, even if the shutter speed is faster, meaning that you must avoid photographing moving objects. Unlike most Panasonic cameras, Olympus did not compromise on the image quality when using the electronic shutter mode, meaning that you don't get the (very slight) reduction in dynamic range with the electronic shutter.

Wednesday, 1 April 2015

Olympus OM-D E-M5 Mark II High Resolution Mode

The headline new feature of the Olympus OM-D E-M5 Mark II is the high resolution mode. The camera is not the first to take multiple pictures while shifting the sensor, to achieve a higher image quality. The Hasselblad H5D 50c takes six picture for a total of 200MP resolution.

However, the E-M5 Mark II takes this feature to the affordable enthusiast market. By taking a total of eight pictures using the electronic shutter, while shifting the sensor, it achieves a whopping 64MP resolution (available using RAW only, the JPEG output tops out at 40MP).

But is the resolution really twice that of the ordinary 16MP output? That is what I am looking into here.

To test it, I have taken the same picture at 12mm using the high resolution feature, and at 24mm using the normal exposure. The pictures were taken with the Lumix X 12-35mm f/2.8 (my review), which is the best M4/3 lens I have used.

Saturday, 28 March 2015

OM-D sensor shift in action

I previously looked into the effectiveness of the sensor shift image stabilization of the new E-M5 Mark II for video use. Even when using a long lens, it is much more effective than the Power O.I.S. of the Lumix X 35-100mm f/2.8.

Here, I'll be looking into how it actually works. By removing the lens, it is possible to look straight into the sensor, to see how it moves during video recording. To video record the sensor, inside the lens mount, I put the Lumix GH4 with the Samyang 7.5mm f/3.5 fisheye lens pointing straight into the E-M5:


For an even lightning, I put some white paper around the Samyang fisheye lens. The lens was set to the closest focus distance, and f/8 for sufficient depth of focus.

Tuesday, 24 March 2015

GH4 vs E-M5 II: Video image stabilization comparison

The Olympus OM-D E-M5 Mark II has a number of firsts in Micro Four Thirds: The first camera to have a sensor offset high resolution mode, the first Olympus camera to feature electronic shutter (called "Silent shutter" by Olympus), and a well functioning in-camera image stabilization feature that also works during video recording, which I am testing here.

To make the test very challenging, I used long lenses on the cameras.

On the E-M5 II, I used the Olympus M.Zuiko 45mm f/1.8 (my review) at f/2.8. As the Olympus camera crops the sensor a bit when recording 1080P footage, this lens corresponds to about 60mm in video mode, or 120mm in equivalent focal length terms, which is a quite long lens.

The Lumix GH4 was fitted with the Lumix X 35-100mm f/2.8 (my review) set to about 60mm, f/2.8. I set the lens to 60mm to match the field of view of the Olympus camera, when recording video. The GH4 does not crop the sensor when recording 1080P footage, thankfully.

I used OIS on the Panasonic Lumix system, and IBIS (In-body image stabilization) on the Olympus system. I only had the IBIS mode (mode 2) initiated on the OM-D, not the IBIS+digital stabilization (mode 1).

Friday, 20 February 2015

More creative potential with Wifi

The camera makers are fighting a battle against smart phones: People want to be able to share their pictures on social media, and this is very easy with the smart phone camera.

To increase the connectivity of cameras, Wifi has become a must have feature. And it does make it more easy to share your pictures with a connected device.

But Wifi also allows you to remotely control the camera, which is a very cool feature. Here is an example where I used it to take close up pictures of birds.

I used the Lumix GH4 with the Samyang 7.5mm f/3.5 fisheye lens (click for my reviews).

To avoid getting dirt on the camera, I covered it with a transparent plastic bag:


I then placed it on the ground near some pigeons, and threw some bread crumbs in front of the lens to attract them. When using the smart phone app, you can see what the camera sees, and can remote control the shutter. It looks like this on the phone:

Thursday, 12 February 2015

Product news

We've had the CP+ trade show in Yokohama, and the major camera brands have been showing their new stuff. Here is a short summary of mirrorless camera news.

Olympus


The big news from Olympus is the new OM-D E-M5 II. It looks a lot like the the predecessor, but has some improvements to the ergonomics, including a fully articulated touch LCD screen.


The new feature which is going to sell the camera, though, is the new sensor shift high resolution mode. It works by taking eight consecutive images, while offsetting the sensor. First, four exposures offset by one pixel in the two directions, designed to overcome the limitations of the Bayer sensor.

Monday, 2 February 2015

Mirrorless camera statistics from Japan

BCN ranking is a source for Japanese camera sales statistics. Looking at historic statistics from BCN, I have compiled this chart of the market shares of mirrorless cameras.

For the years 2009-2011, it is based on the 20 most selling camera models in Japan, including DSLR cameras. For 2012-2013, it is based on the 20 most selling mirrorless cameras. For 2014, it is, apparently, based on all mirrorless camera models. I skipped 2008, since it only contains one single mirrorless camera, the Lumix G1, giving a 100% Panasonic market share.

Sunday, 25 January 2015

New firmware for Lumix 35-100mm

Panasonic recently announced a new firmware for the Lumix X 35-100mm f/2.8 pro grade tele zoom lens (my review). Click here to download the firmware version 1.2.

Here is the lens mounted to the Lumix GH4:


So what exactly does this firmware update do? If you follow online forums, you will see some few, but quite vocal, people complain about "micro jitters" when recording video using this lens. Based on the press release explanation from Panasonic, it might appear that the firmware addresses this issue: