Using V-Log L with GH4

Some months ago, Panasonic released a V-Log L video option for the Lumix GH4. Here, I intend to give a short introduction to what this is, and how you get started with this video profile.

This is, of course, not a complete course. That would require a lot more than a short read. But this is intended to show you what V-Log L is, and how you get started, if you are interested.

For most people, myself included, V-Log L usage is not a big deal. Most of the time, I am happy with the normal video output from the camera, and I don't spend the extra time and effort with the V-Log L profile. So keep in mind that this is optional: You can still enjoy the camera without caring about V-Log L.

Some would compare the V-Log L profile to using the RAW image format, rather than JPEG, when taking still images. It is not exactly that: The video is still compressed (unlike RAW), and it is processed (not straight from the sensor, like RAW normally is).

However, this comparison still makes some sense, as you would use the V-Log L output much in the same way as you would use RAW: To be able to make adjustments to the colour and tone curves of the image. For video, this process is called "colour grading".

When enabling the V-Log L profile, the output is flat. What I mean with flat, is that it looks grey, with little colour saturation, and little difference between the light and dark areas. If you uploaded the video straight to Youtube, people would think it looks quite boring.

That is why you go through the grading process first. Here, you apply a Look-Up Table (LUT) to convert the flat profile back to something that looks normal, and you can apply colour and tone corrections on top of that.

Recording in V-Log L

First of all, of course, activate the V-Log L profile, and you should see the corresponding symbol in the top left corner:

As you see here, the image is "flat" in the sense that it is grey and has low contrast.

You can use the normal exposure modes also for V-Log L. However, keep in mind that the camera will often underexpose in V-Log L, and mostly you'll want to correct for that. I usually leave the exposure correction at +1 stop when using V-Log L, as you see above.

For "run and gun" use, where you have varying lightning, this works well. I guess some seasoned videographers would frown at using automatic exposure, as opposed to full manual, but I don't think you should worry about that. Using auto exposure is a good way to get started.

If you use manual exposure, you'll need some tool to make sure that you have the right exposure. As the profile is so flat, it is hard to notice from the screen if the exposure is too low or too high. The "zebra" stripes is a good tool. Set to "Zebra1":

And adjust that to 80%:

That way, anything which is overexposed (burnt out) will get the zebra stripes in the display. Adjust the exposure so that you are just not getting the zebra stripes, for the optimal exposure. Some zebras are ok, but keep in mind that those areas don't get any details in the final output, due to overexposure.

In V-Log L, you can only use ISO between 400 and 6400. You can still use Auto-ISO.

Editing the video

As the video output is so flat, you cannot just upload it to Youtube, you must first grade it. I have been using Adobe Premiere Pro, but most serious video recording software can handle this.

You bring the footage into the editor as usual, and note that it still has the flat look, as it is not yet graded.

To get the right Look-Up Table (LUT), you can get Panasonic's official one from here, scroll to the bottom and look for "LUT (Look-Up Table)." This is a zip file, and inside you will find a file called "VLog_to_V709_forV35_ver100.cube". This is the one you input into the video editor software.

Add the Video Effect "Lumetri Color" to your video stream. Inside this effect, choose "Custom" from the "Input LUT" option. Here, you select the file you just downloaded from the Panasonic site.

After having done this, you can select the output style you want in the "Look" section. I have just selected "Neutral". You can look at the other ones as well, and see if you would like to test some retro film looks. And remember to select "Active" for it all to work.

This makes the video look normal again:

On top of this, I thought the shadows had some green tint, so I moved the centre of the "Colour Wheels" a bit for the Shadows and Midtones. Also, I took down the Saturation a bit, as I thought the colours were a bit strong:

These colour wheels are central to tweaking the video. A common cliche the last years, is to push the shadows towards the blue, and the midtones towards orange. This creates a contrasty effect, and makes the skin tones stand out a lot. You'll see this effect used a lot in, e.g., "Transformers" and "Iron Man 2".

Using an effect like this is going to make your video look modern today, but look dated in some years time. I prefer to keep them more neutral.

After having done all this, I can render the video as usual. Here is the output in Youtube:



Sadly, the focus was a bit off during a lot of this movie. I used the Lumix 25mm f/1.4 lens at f/1.6 and didn't foresee the focus issues it would have. The problem here is that the microphone in the front attracts the focus some of the time, and when the musician moves, the background looks more stable and easier to focus on for the camera. I could have prefocused on the musician's face, and turned off autofocus, that would have solved the problem. This is a lesson learnt for me.

The exposure was: f/1.6, 1/60s, ISO 640.

This video could have been graded better still. As you see, the face of the musician is a bit too red. However, I had a hard time finding the right white balance. I guess an experienced grader would have made this far better.

Conclusion

The V-Log L video option opens up for more possibilities to use custom video profiles in post processing. However, you need to spend more time on editing the video files, and you must invest in an editing software, like Adobe Premiere Pro.

Finally, you can get by pretty well without worrying about the V-Log L at all. Here is an example video I recorded using the normal video profile (not V-Log L), and uploaded directly to Youtube without any post processing:



Most of the time, this looks totally ok. Personally, I am not using the V-Log L a lot. For normal hobbyist use, the standard profile is just fine.

For  a professional, having V-Log L is crucial, since it allows for colour grading clips to match, even if they are recording under different lightning condition, or even by different cameras. But for amateurs, it adds an additional step of post processing, which may not add much extra value.

OM-D E-M5 II video quality

The Olympus OM-D E-M5 II is the first Olympus M4/3 camera with a real promise to quality video output. It features 52Mbps output in the "SF" (Super Fine) mode, at 1080p, 60fps (or 50fps if you are in a PAL region country). So how does the video compare with the Lumix GH4, the reference in terms of M4/3 video?

First of all, let's note that there is disappointing news about the E-M5 Mark II video: The sensor is cropped slightly, making your lenses less wide than you expect. Here is an illustration of the sensor area used for video:

This corresponds to an additional crop factor of 1.16. Or in other words, the Olympus 12-40mm f/2.8 becomes 14-46mm when using the video mode. So the effect is not very dramatic.

This crop during video is not uncommon, by the way. The Nikon D7200 can only do 1080p video at 60fps with a 1.3x crop of the sensor. And that is Nikon's premier DX DSLR. While we wait for the D400.

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 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).

Lumix GH4 Review

The big news from Panasonic this year is the Lumix GH4. There is a tradition that the version number four is dropped when incrementing a camera model name. For example, there was never a Lumix G4 or GF4. The reason for this is that the word for "four" rhymes with the word for "death" or "disease" in some Asian languages.

However, there are two reasons why Panasonic still used the model name "GH4": One is that professional cameras often still carry the number four. We have the professional Nikon D4, for example. The manufacturer probably reasons that the users of a professional camera is less likely to be superstitious.

The other reason is that the main new feature of the GH4 is 4K video. So it makes good sense to use the model name GH4.

From the outside, the GH4 looks very much like the predecessor GH3:

The body is molded slightly differently over the flash, but other than that, the shape of the camera bodies is pretty much identical. The button layout is also the same. However, there are some small, but important differences.

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?

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?

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:

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.

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.