Thursday, 29 May 2014

GH4 focus performance during video recording

Recent Micro Four Thirds cameras have very good autofocus performance for still images. Mostly, the performance is among the best in this class, certainly better than DSLR cameras in live view mode. However, there is one area where mirrorless cameras don't perform well at the moment, and that is continuous autofocus: Both during video recording, and for photographing moving objects, e.g., for photographing sports and birds.

Some camera manufacturers have been trying to solve this by adding phase difference sensors (PDAF) on the imaging chip, like the Nikon 1 and Sony E-mount cameras. However, the real world benefit of that solution is still somewhat undecided. The Nikon 1 cameras appear best in this respect so far.

Panasonic have said in interviews that the on-sensor PDAF solution is not going to be used for their Micro Four Thirds cameras, at least not anytime soon. Rather, Panasonic expects to achieve better continuous autofocus performance by using faster image readout from the chip, better image processing algorithms, and more processing power. Have they achieved this with the most recent Lumix GH4?

Sunday, 25 May 2014

1080p video comparison, GH3 vs GH4

I guess most people who buy a Lumix GH4 do it to use the 4K video feature. However, it is still a very good 1080p video camera, as well. Here, I am comparing it head to head with the Lumix GH3.

I used the Lumix G 14mm f/2.5 lens on both cameras.

The test


Both cameras were mounted to a Desmond Mini Dual Camera Bracket, typically used for stereo photography. On the lenses, I have used 46mm to 37mm step down rings as hoods. They do a good job of keeping the front lens elements safe from accidents, in my opinion, while also keeping out some stray light. If you want to use them, you also need a 37mm front lens cap.


Wednesday, 21 May 2014

Free 4K video editor

With the launch of the Lumix GH4, the least expensive 4K video system camera so far, there has been an increased interest in video editors capable of handling 4K resolution.

For years, I have used the kdenlive free video editing software. When you look at the list of video resolutions to choose from, it may seem that the highest resolution you can edit is 1920x1080.

However, it is a simple thing to add 4K resolution to the list of formats to choose from. Then, you can edit 4K video just as easy as 1080p. Here's how:

Sunday, 18 May 2014

Do you need new SD cards for GH4?

Recently, there has been a lot of talk about the Lumix GH4, and that you need the new, very expensive, UHS Speed Class 3 (U3) cards to use the 4K feature. Well, do you?

My answer is: You probably don't need any new SD cards. Keep reading to see why.

Card speed ratings


When you buy an SD card, you pay for three things: The brand name, the capacity (size), and the speed. The branding is in fact quite important for the price, which is the reason why counterfeited cards is a big problem. You can read about my experience with counterfeited SD cards here.

Saturday, 17 May 2014

GH4 AF during video performance

For still image use, and with non-moving subjects, the autofocus performance of Micro Four Thirds cameras is now very good. Nothing to worry about at all. However, an area which is still a problem is continuous autofocus during video, and for following moving subjects.

In this area, other systems are better. For example, the Sony SLT A77, since it has a semi-transparent mirror used for traditional PDAF, which also works during video recording. Another system which does this well, is the Nikon 1 mirrorless system. With on-sensor PDAF sensors, it implements AF-C rather well.

Still, Micro Four Thirds cameras get better at this. When the Lumix GH3 was introduced, I found that it did much better than the GH2, probably due to better and faster image processing algorithms. Can the Lumix GH4 improve this further?

To test this, I used pairs of the same lenses on the GH3 and GH4, to compare them head to head:


From front to rear: Lumix G 14mm f/2.5, Lumix G 20mm f/1.7, and Sigma 30mm f/2.8 DN. More about the lenses later in this article.

Sunday, 11 May 2014

Worse image quality with E-shutter?

Electronic shutters have been used for years in compact cameras. Larger sensor cameras generally need a mechanical shutter, though. Reading all the sensor values of larger sensors takes more time, and an electronic shutter often cannot do it fast enough.

The Lumix GH3, for example, has an electronic shutter, but it takes 1/10s to read out all the rows, making it less useful. Read more about the rolling shutter artifacts associated with the electronic shutter here.

An interesting Panasonic sensor data sheet has popped up. We don't know for sure, but it is widely believed that this sheet describes the sensor sitting in the Lumix GX7 and GM1. Some also speculate that it will be in the upcoming Lumix GH4.

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. This indicates that you lose two bits of dynamic range if you use the electronic shutter mode of the GM1. Is this a problem? I'll try to find out with a comparison.

Wednesday, 7 May 2014

New Cine lenses from Samyang

When Samyang, the South Korean optics company, designs a new lens, the make the most out of it. Not only do the market it under a number of different names, including Rokinon, Bower, Walimex, Vivitar, Falcon, Opteka, Polar and Pro-Optics. They also make the lens design available with a number of different mounts, usually many mirrorless and DSLR mounts.

To top this off, they also tend to make two versions of the lenses, even in the same mount. They often make special "Cine" versions of existing lens designs. The Cine versions are made specifically for video use. They recently launched Cine versions of three lenses.

Sunday, 4 May 2014

100 years of Leica

It is hundred years ago now that the first Leica prototype was made. The famous "ur Leica" prototypes were made around 1913-1914 by Oskar Barnack.


The genius of the camera was not the interchangeable lenses (that was introduced in 1930 for the 39mm screw mount, and in 1954 with the Leica M3 and the M mount), and not the rangefinder focus method (Leica II in 1932). The genius of the ur Leica was the use of ordinary 35mm motion picture strip film in a compact camera.

Saturday, 3 May 2014

Sigma 60mm with rubberized focus ring

In 2012, Sigma released their first Micro Four Thirds lenses, the 19mm f/2.8 and 30mm f/2.8. They are not impressively fast, but well performing and relatively inexpensive.

The lenses were updated already one year later, in 2013. However, only the exterior was changed. The lenses lost the ribbed plastic focus rings, replaced with a smooth metal exterior. At the same time, a new lens was released, the 60mm f/2.8. The three lenses are seen below:



Thursday, 1 May 2014

Product news: Small is the new black

Looking back in time, it is now around ten years ago that digital system cameras became fairly common. Cameras like the Canon EOS 300D (Digital Rebel, 2003), and the Nikon D70 (2004) made this possible, by offering affordable and well performing system cameras to a wider audience. Further, the cameras could use existing lenses from earlier film based cameras, that many already had lying around.

What followed was a period when having a large size camera was trendy. A large camera looked professional, and that was a look often favoured by the consumers. Around the same time, we got the "thin DoF craze", where it became trendy to use large aperture lenses, e.g., relatively inexpensive 50mm f/1.4 normals lenses, for a very selective focus effect.

Times are changing now, and we are seeing more and more that camera news is all about size: Small sized quality cameras has become trendy.