INTRODUCTION
Canon introduced some pretty amazing specs into their new camera. With the ability to record HD, 2K, UHD, and 4K internally up to RGB444 12-bit, you can be sure the camera will be up to any challenge. But at the core, what really matters is not only the resolution, but how the camera interprets the image information. What are the various gamma settings available? How does the camera handle over and under exposure? What is the camera’s dynamic range? Is there noise, and if so, at what ISOs? I hope to answer all of these questions in this post.
You can download all the reference video files in full quality here. (As long as storage allows…!)
Gamma settings
The Canon C300 MK II comes packed with a wide variety of gamma choices. With the release of the camera, Canon has introduced a new Cine Gamma, called Canon Log 2. This gamma profile flattens the image much more than before, likening this new profile to Arri’s Log-C or Sony’s S-Log. With this gamma, you have various color space options as well. For these tests, I chose Cinema Gamut when in Log2. The camera also ships with some old favorites. Here is a list of all available options:
Canon Log 2: Cinema Gamut
Canon Log 2: BT.2020
Canon Log 2: DCI-P3
Canon Log 2: BT.709
Canon Log
Wide DR
EOS Standard
Normal 1 (Standard)
Normal 2 (x4.0)
Normal 3 (BT.709)
Normal 4 (x5.0)
Throughout this review, I will be looking at the presets Log 2 and Log. These are the two gamma settings that need critiquing, as they are the ones that will not only be used the most, but also the ones we will debate over when, where, and how to use them. With that said, I will discuss the Rec 709 profile in different situations for a point of comparison. When setting up these tests, I used my Sekonic L-758Cine light meter set to ISO 800, which is Canon’s rating for the camera. I felt it was important for me to know what the various gamma settings look like when exposing them to a meter reading, thus telling me how much I should over or under expose my image for any given setting. As you will see below, each gamma represents values differently.
In the first setup, I shot outside on a clear day, where there was both bright sunlight and even shade within the shot. In the shade, the meter read an F11 at ISO 800. This is where I exposed the camera. The bright sun on the background buildings read between an F45 and F64, or 4 – 5 stops overexposed. Take a look at how differently each gamma setting interprets the scene.
In Canon Log 2, we have a smooth gradient transition from our shadows to our highlights. Midtones are not dramatically under exposed, yet the camera easily holds an exposure, even in the brightest lit portions of the frame. This setting will require the most amount of color correction though, so be aware.
In Canon Log, there is increased saturation and contrast in comparison to Log 2. Midtones are brought down, relative to the meter, and we start to lose some information in the highlights.
In Rec 709, the scene is normalized in terms of exposure, saturation, and contrast, so this would be an acceptable gamma setting when color correction is not an option. This will produce good looking images ready for edit right out the camera, but there is a significant loss in highlight retention.
Here is a video of the Log 2, Log, and Rec709 gamma settings.
This daytime exterior scene give us a good sense of what is happening with our midtones and highlights. But what about the shadows? Let’s take a look at a night interior scene. Many thanks to my fiancé, Sarah, for sitting in giving me something nice to look at while putting all this together! You can see that the midtones, while a little low, do not appear underexposed. The shadow and highlight detail retain strong. The dark back wall is 4 stops underexposed and the stove light is 4 stops overexposed. At ISO 800, there is little noise in the image.
In Log, the midtones appear slightly underexposed in comparison, which pushes the shadows farther into darkness. The extreme highlights start to push the limit as well. Yet, this gamma setting can hold up to color correction well, especially now that we are able to record in either 10 or 12 bit in HD and 2K and 10 bit in 4K. The image appears to have even less noise than Log 2 at ISO 800.
In these examples, we’ve looked at various gamma settings when exposed properly, and how they render a scene when done so. Let’s now look at Canon Log 2 and Canon Log when under and over exposed.
Over & Under Exposure Tests
While the previous test is necessary when judging gamma settings under ideal situations, the real test comes when we look at underexposing and overexposing an image. This is useful both when trying to determine the effective latitude, as well as knowing whether you feel comfortable pushing the limits of your shot. Let’s first look at the night interior scene once again, but with a map of exposure readings.
Now let’s take a look at Canon Log 2 5 stops underexposed to 5 stops overexposed. Following are waveform readings of each stop to see how the gamma setting holds information.
And the same 5 stops under and over at Canon Log.
Dynamic Range
Now that we’ve seen 5 stops underexposed and 5 stops underexposed, WHAT IS THE DYNAMIC RANGE OF THE CANON C300 MK II??
Canon released the camera with specifications stating 15 stops of dynamic range. This was a HUGE announcement, but of course people were skeptical. Since the release of the camera, a few people have done their own tests to determine if this number was accurate.
The dynamic range of a camera tells you how many stops of light you have from black to white. This helps you determine how far over or under exposed you are willing to let a window blow out, or knowing whether you want a 3:1 or 5:1 contrast ratio on your subject.
I feel using a chip chart for testing dynamic range is a slippery slope. Most high quality charts are glossy, so as to produce as close to true black as possible. But this can also lead to reflective points on the chart that do not represent the proper luminance value. If you can create a perfect testing environment, then these work great. Also, many charts still do not represent a range wide enough for testing cameras. The chart I have only gives me a 12-stop gradation. So when you want to test how many stops over and under middle gray you can go before you hit pure black or pure white, why not do just that?
I set up a gray card and lit it evenly with a soft light source. I set the camera to Canon Log 2 at Cinema Gamut color space, at an ISO 800, the base setting of the camera. Then I simply over and under exposed the camera one stop at a time until I flat-lined at either 0% or 100% on the IRE scale. There will probably be some minor fluctuations in values, depending on the lens quality and f-stop characteristics, but these are factors that will exist in the real world, so I am fine having them part of my test. Because remember, the real reason for testing all of this is to give you a more accurate understanding of the equipment you are working with.
In the image above, Canon states that at ISO 800, the base setting, the camera should give you 6.3 stops over middle gray and 8.7 stops under (or 7.7 below when you account for middle gray as its own exposure). When I did my test, I also found that the first fully clean exposure with no clipping was in fact 6.3 stops over. When underexposing, I found that 7.7 stops under middle gray was already bleeding with the previous exposure value, leaving me with 7 stops under middle gray as my bottom out point. This leaves us around 14-14.3 stops of dynamic range.
ISO Noise
Noise is always a factor worth examining in tests like this. While the C300 MK II gives you the ability to shoot high ISOs, the image may not always look that good. When you have to push the limit on a shoot, just how far are you willing to go?
These videos show an incremental step of the ISO range from 160-25,600 at various gamma settings. This was shot with the port cap on the camera, so we see what’s happening on the naked sensor.
It’s interesting how with Log 2, you cannot really go above ISO 800 without starting to see some real noise, but in Canon Log or Rec709, you can push it safely up to ISO 6400! This is an important point to note. Next, we look at our daylight exterior setting at Log 2 at various ISOs. How noticeable is the noise when bright and sunny?
After seeing the ideal limits experienced in pure black, it was nice to place that information into a bright, contrasty scene. While it can be hard to see the noise with so much information in the frame, looking at the woven deck chair reveals noise beginning to develop at the exact points we saw from the black test. Also, notice the significant green shift when we move above ISO 20,000.
Lastly, we look at our night interior and do the same thing. How does the noise react in the shadow areas?
Another interesting test is looking at how the sensor interprets its Gain/ISO, and is it better to shoot a higher ISO in camera, or push the image later in post? In this example, I took one image shot in-camera at ISO 6400 and another shot from the over/under test at ISO 800, 3 stops underexposed. I then adjusted the exposure in post to match to the native ISO 6400 shot.
It is quite apparent the sensor does a much better job suppressing noise at higher ISOs than when pushing the image in post. Just like we saw high the extremely high ISOs, there is a substantial green shift in the noise when you push the image. So if anything, when shooting in extreme low-light, its probably better to up the ISO and overexpose slightly, then hope to push it in post.
Conclusion
After looking at the various Gamma settings, over and under tests, and ISO noise, here are my final thoughts on settings.
Canon Log 2 is an impressive gamma curve for giving you the most out of your image. With an effective 14 stops of dynamic range, you can tackle contrasty scenes with a gentle smoothness. It gives you plenty of information across the exposure range, but requires a lot of color grading to get a pleasing final image. With the introduction of noise after ISO 800, I will be choosing this gamma curve when I have solid control over my lighting and can moderate my aperture with NDs to always stay at an ISO 800. This makes using Log 2 tricky in most documentary settings, but ideal for narrative work.
I am still impressed with Canon Log, in that it gives you a nice range of exposure without requiring as much work in color correction. Being clean up to ISO 6400 is a huge factor as well. I think this will remain my go-to gamma setting in documentary settings, while utilizing Log 2 in special situations when the going gets tough.
Doing these tests has deepened my understanding of how the camera sees and interprets the world, thus allowing me to better capture images. Knowing where the camera excels and where it has limitations keeps my mind free to think more about the creative and less about the technical. I urge you to do your own tests and get comfortable with your camera. There are no right or wrong tests to perform, only the ones that help you get the results you are looking for.