Field Test: Canon Log Comes to the 5D Mark IV

As previously announced filmmakers can finally celebrate the arrival of Canon Log to the 5D Mark IV, with the release of details on the paid upgrade and the availability of a body with the function pre-installed. However, if you aren¡¯t so in tune with the world of Canon¡¯s Cinema line, you may be wondering what exactly Canon Log is and why or when you would want to use it. Or, perhaps you are very in tune with cinema gammas and want to see how the 5D Mark IV footage holds up when this specialized profile is used. We made sure to take out a camera with this capability to see how it performed, and provide some tips on how to get the most out of it. And if you just want to skip right to the footage, check out the video at the end of the article.
To begin, we should provide a basic overview of what Canon Log aims to do, and why filmmakers will appreciate it. Much in the way users would set low-contrast picture styles or settings to retain as much information as possible for the post-production process, Log gammas essentially do the same thing, but to a much greater and more technical extent. By using a logarithmic curve, the profile can reposition the data to cram as much information as possible into the compressed 8-bit 4:2:2 4K or 4:2:0 Full HD files. This results in a much greater dynamic range being recorded, though it does mean that the super flat-looking footage will require a knowledgeable hand when it comes to editing and color grading.

After that extremely simplistic overview of log, it¡¯s time to look at the images to really gain a better understanding of Canon Log in the 5D Mark IV. Examining the raw footage, it is easy to see that the profile suppresses the highlights and pushes the shadows, meaning the footage looks somewhat ugly compared to the Neutral style. Once we apply a LUT, we can quickly see the advantages offered by the function. In this shot from beneath a bridge, you can see where the highlight starts to lose information and creates a harsh transition, whereas, in the graded log footage, you have a smooth gradation with a more natural coloration. The advantage can be extremely subtle, but it is something to consider if you want your images to look the best they possibly can look, and perhaps obtain the highly desired ¡°film look¡± with natural highlight rolloff.

DaVinci Resolve Studio Screenshot

Stepping back a bit, I should explain the process with which I shot and edited the footage. I captured the video with both the log and neutral versions, using the same settings, providing a balanced exposure per the in-camera meter, which is how Canon advises that the images be captured. This setup ensured that everything remained the same across the shots for comparison and that the resolutions remained consistent. I used the best mode available in the Mark IV, which is DCI 4K (4096 x 2160) at 24.00 fps and the MJPEG format saved to a CF card. Then I converted the video to ProRes 422 LT and brought everything into Blackmagic Design¡¯s DaVinci Resolve Studio. From there I applied Canon¡¯s Canon Log to Wide Dynamic Range LUT and performed light edits to enhance contrast and color. What you are looking at is a DCI 2K output and stills from DaVinci, which, for all intents and purposes, show off everything we need.
One thing that I quickly found was that color is much easier to work with on the Canon Log footage than with the Neutral style. The smoother gradations and lack of a baked-in look provide the best starting-off point for performing grades. It also looked more accurate to the scene after minimal edits were performed, whereas the Neutral images seemed just a tad off when compared side by side. In shots where a light source or strong highlight was present, it very obviously could retain more information and dynamic range. Looking at the following images, you can see the extra data being retained, while keeping enough shadow information so that users have control over how far to crush or pull back the darkest parts.

For the most dynamic range possible, Canon recommends that you stick to ISO 400, which is the base sensitivity for Canon Log. You can use it at ISO 100 and 200, but you will lose a little bit of range and, when you move into the higher ISOs, you increase the risk of noise entering the frame. This leads me to another point about a warning Canon posts in its information, about how it is possible for some noise patterns to appear in Canon Log that otherwise wouldn¡¯t be an issue during normal recording. I noticed that this only showed up in the darkest parts of the images and when I was pushing the shadows up a bit to bring back data. So, I would recommend evaluating the scene to determine whether you will benefit from log before deciding to shoot in it. For scenes with wide dynamic ranges, the benefits are obvious and well worth the risk, but in lower-contrast shots, it may introduce noise that you could¡¯ve avoided with a standard profile. See the following shot for an example, though I will point out that the noise is practically unnoticeable if you don¡¯t go looking for it and, with a bit more editing, you could effectively eliminate it.

One thing I want to come back to is how colors are handled in the Canon Log footage. I found it to be much more natural and true-to-life than the standard profiles. Now, in some cases, the footage turned out to be quite close to one another, but in others, such as flowers with bright, highly saturated hues, Canon Log really helped in post. These colors tended to become too vibrant or overpowering in the neutral style, which is notable because the style has had saturation turned all the way down. This resulted in harsher transitions and a bit of an unnatural look and a potential for posterization. See this pink flower for example, where both the pinks of the flower and the surrounding the greens look a little bit better in the Log footage¡ªin my opinion, of course.

Overall, the advantages offered by having Canon Log as a function in the 5D Mark IV are well worth it. This is an advanced feature for video, however, and if you are interested in it, I would recommend that you read up more about log gammas and editing before you start using it for critical work. Also, one thing I didn¡¯t mention is for users of Canon¡¯s Cinema cameras who will benefit from a more unified workflow if they decide to use a 5D Mark IV as a B camera for a C300 Mark II, for example. If you are serious about video and want to make sure you can capture the best footage possible, Canon Log is something you will want in your toolbox, without a doubt.