Log. What is it, why are there so many different kinds, and should I be using it? These questions can all be easily answered. If you carefully consider your shooting conditions, equipment and plans for post-production, you can determine whether shooting in log is right for you and which profile is best for your needs.
Log, as you may know from this helpful guide, is short for logarithmic profile. Shooting in log allows your camera’s sensor to capture and output more detail. Log delivers a broader dynamic range without the extreme memory and post-production demands of shooting in full RAW.
Shooting log footage
Straight out of the box, most consumer and prosumer cameras will give you a video file recorded in the REC. 709 picture profile. REC. 709 is the standard for all HD video. However, it reproduces a much smaller dynamic range than many cameras can actually capture. Some professionals like to shoot in RAW because it allows you to manipulate every aspect of your video data. For many people, though, the enormous file sizes and increased post-production time are simply too much. A much simpler method of augmenting your footage quality is to shoot in log. By letting your camera do the heavy lifting — debayering, edge refinement and noise management, for example — the log process gives you higher quality footage, more manageable file sizes and a simpler workflow.
RAW, although intensive, does have some unique perks worth mentioning, however. Other than being the absolute highest quality any given camera can output, RAW video data can be put through new manufacturers’ sensor profiles, edge refinement and noise management at a later date. This means you can give dated data the look of current state-of-the-art footage.
Is log right for me?
Log or ‘flat’ picture profiles are a great way to improve the output from your camera. Simply put, they condense what your image sensor is capturing so that it’s imaging power is focused more on details than intensity. This gives you a larger dynamic range by about one half-step on average. Your sensor captures more detail in the reduced highs and lows. Then, later, you or a color professional can simply add back the contrast and saturation to the image or apply a specific LUT, leaving you with a vivid detailed image.
Looking at some online resources, it may at first appear that shooting in log will improve absolutely everything you shoot. In many instances, however, Log is not necessary and can sometimes even damage your footage.
Limitations of 8-bit
First and foremost, if your camera shoots video in 8-bit color, log may not be the right choice for you. Using Log on a camera with 8-bit color depth can introduce noise and color banding. It can also make skin tones appear unnatural if pushed too much in post. 8-bit log footage does not have enough color information to allow even a modest amount of exposure adjustment or color correction without displaying the artifacts mentioned. If very little grading is required, you may be able to achieve a larger dynamic range with log.
On the other hand, wasting an entire shooting session could really hurt your project. The best way to deal with this issue is to test shoot exactly the situation you will be filming and analyze your graded footage. If your camera allow it, you can also record to an external recorder that supports 10-bit or higher color depth.
An unnecessary burden
If you are working with studio conditions where you can control the lighting or you are producing content on tight deadlines, log may not be a helpful tool for you. Properly lit scenes give you a dynamic range that cameras are built for. That means your camera will already be giving you the best quality it can output without the help of log. The extra dynamic range you can get from log may also be insufficient for those who value speed over quality.
How and when log can help you
Log can be a great tool for the camera person who knows they will have time to edit their footage in post and would like to get more detail in footage that may not be perfectly lit. If you shoot in a run-and-gun style quickly transitioning from light to dark settings, log is perfect for you. The added dynamic range will give you footage that can be pushed farther than your standard footage. This could potentially save shots from being washed out or too dark. At the same time, the extra detail from log will give you a more cinematic look. Not to mention you’ll have more usable footage at the end of the day.
Why are there so many different log profiles?
The logarithmic function you choose will influence your final results. This is true whether it be Log C, V-Log, S-Log, C-Log or the many other options now available. Manufacturers are now making many different profiles to give you more control in different settings and to work differently in post.
S-Log is a good example of how the functions can return varying results. Sony offers two different S-Log profiles: S-Log2 and S-Log3. These perform better under different circumstances. S-Log3 has characteristics closer to those of scanned film and allows for better reproduction of gradation characteristics in shadows and the mid-tone range than S-Log2. So say for example you are shooting from a dark room looking out into a smaller, brighter area; S-Log3 will allow you to capture more detail in both areas but lean towards the darker area. This will give you more gradations in the dark area. Sony, in general, recommends using S-Log3. However, if you’re shooting in the opposite setting, say shooting into a darker area from a lighter one, S-Log2 will return better detail and gradations in the predominantly lighter area.
Since there are so many different Log profiles specific to each camera and camera manufacturer, the best thing to do is to refer to your camera guide or manufacturer’s website to understand the benefits of each different profile. Testing may be your first instinct. However, some benefits may be hard to detect with the naked eye. A little research will point you in the right direction before spending too much time testing all of your possible choices.
Working with log
Although log can improve your video output after post-production, it does present some obstacles while shooting. Most notably, it can be difficult to properly expose while shooting in log. The image you will see when using log in your viewfinder will look washed out and lighter than standard. This makes it difficult to use your experience to properly expose. Don’t be afraid to go back to the basics to figure out how to expose a scene. Exposure tools like your histogram, waveform and/or zebra stripes can be immensely helpful in retraining your eye to the proper settings for any given scene.
One drawback to shooting in log is additional noise. A helpful technique to mitigate possible problems is to ETR, or Expose to the Right, and overexpose just a hair. Opinions vary, but overexposing your shot by about one or two stops ensures that shadows will not need to be lifted in post — the main cause of additional noise when shooting in log.
Many companies also have an included exposure assist with log in mind like ‘Gamma Assist’ in SONY cameras or V-LOGL View Assist in Panasonics. Search your camera to see if there are any built-in exposure assists that will help you set the right exposure settings while shooting in log. Some cameras and external monitors also allow you to load LUTS or the standard REC 709 color space into them and view an image closer to what you will have post color correction. Search your camera for the best options to help you use log to the best of your abilities.
So, to log or not to log?
If the setting and demands are right, log can be a very helpful tool. It can improve your dynamic range and give you more usable footage at the end of any shooting day. But remember before jumping in, you should build your confidence before using it on any important shoots. This will give you a chance to see if the extra dynamic range is worth the added post-production work, how to properly expose your scenes and the kind of added quality you can begin to look forward to with log.