Ryan E. Walters, Cinematographer

Cinematic Excellence at 24 Frames a Second

Some Like It RAW. Part 02: Low Light


Welcome to Part 02 of Some Like It RAW, where I am comparing the Arri AlexaBlackmagic Cinema Camera, and the Red Epic. My goal for these tests is to explore how each of these cameras handle real world shooting environments. Part 01 explored how these cameras handle IR pollution. In part 02, I test the limits of low light levels, or underexposure. Continue on to watch the 11 minute video, read my summary, and get the downloadable RAW frames from each camera.

I'd again like to thank the following people who helped to make this test possible:

Picture This Productions
(Provided the Blackmagic Cinema Camera)
Shawn Nelson
(Provided his Epic)
Patrick Eggert
(Provided his Alexa)
Isaac Marchionna
(Assisted for the shoot)
Laurie Slater
(Was our Talent for the day)
180 Films
(Provided the Cooke 20-100mm Zoom)
Letus
(Provided the cage for the Blackmagic camera)
Schneider Optics
(Provided the IR Tuner Kit)

The more I explore and experiment in my craft, the more interested I am in what happens at the limits of our recording mediums. I am definitely pushing these cameras to their limits in Part 02 & 03 of this series. :) The greats that have gone before us pushed their technology beyond where it was intended to go and broke with convention to make their projects happen. (A great example of this is Barry Lyndon). As I am always desiring to push myself, I thought it was time to explore the limits of today's technology and evaluate the results. By testing in this manner I'll be better equipped to experiment on a project, or push beyond convention and hopefully create my own compelling imagery. If you are looking for clear winners and losers then you've come to the wrong place, as that is not the point of test. The point is to see how these tools perform when they are pushed beyond what is normal, or considered safe. A better understanding what happens at the limits, not only ensures better images when I play it safe, but it will empower me to make more informed choices when I don't play it safe.

Here is the overhead diagram of how I lit these shots. The lighting did not change in-between cameras; it only changed slightly in-between setups. (I flagged off part of the background, and brought the key over a touch).


Below the 11 minute video you will find details of how I determined the underexposure values, a summary of my observations, and the link to the downloadable RAW frames from each camera.



How I Determined Underexposure Values:
I ran two tests to determine the underexposure values for these cameras. For the first test, I took the Sekonic Profile Target II exposures and loaded them into the Lite version of Resolve. Once there, I pulled up the waveform and looked for the last discernible chip that was viewable in the waveform. For the most part, this gave me my basis for my real world ratings.
Waveform from Resolve
Close up of Waveform Reading
For the second test, I loaded the files into Photoshop, and I selected each patch individually to acquire its Median value. As soon as this number stopped decreasing, I knew that I had reached the absolute bottom in exposure. These values tended to go much further than what the waveform in Resolve was telling me. While these values are interesting, practically speaking, they are packed too tightly together, that by the time the images are graded, they will end up as one value and essentially count as one stop. So I don't count them as being of any real world value. It is just a technical exercise.
Selected chip of a -8 EV exposed Sekonic chart in Photoshop
Results of selection
You can download the Profile Targets for all of the cameras from my Sekonic Profile Page. And yes, I freely acknowledge that the Xyla chart from DSC labs is the best chart to use for testing dynamic range. However, its' price is outside of my personal ownership. I have found the Sekonic Profile Target II to be adequate for all practical purposes in camera profiling, and for calibrating my 758Cine & 478D.


Observations & Recommendations:
- Lighting at high EI's is more about controlling spill, and fill levels than it is about "lighting."
- The more these cameras are pushed to their limits, the more expertise, and the greater care that is needed in the grade.
- Each camera has its own look which may or may not suit a particular project.
- My preference is to shoot wide open at higher EI's, which will reduce the contrast of the image, allowing for more subtle gradations in the shadows. (This is good news, as I am typically shooting wide open at high EI's anyway). :)

Alexa Underexposure Limits:
- Maximum: -8 5/6
- Usable: -5 5/6

Blackmagic Underexposure Limits:
- Maximum: -7 1/6
- Usable: -5

Epic Underexposure Limits:
- Maximum: -8 1/3
- Usable: -5 1/6


The following is my personal taste, which may not align with yours. :)

When shooting on the Alexa:
- Work with the camera at EI 800 to get the least amount of noise, even in an underexposed image. An underexposure of 1 stop still yields acceptable noise levels.
- With an underexposed image at EI 1600 cleanup needs to be done, but it looks to be salvageable. (By someone more skilled than myself.)
- An underexposed image at EI 3200 is unusable.

When shooting on the Blackmagic:
- I feel comfortable working with an underexposed image at EI 800 or 1600.
- An underexposed image at EI 3200 is unusable.
- I think that my perception of this camera having less noise than the Alexa has to do with the desaturated image of the camera file, and the use of a wider lens. (By using a wider lens to get a similar field of view, the parts of the image that show noise are magnified less then their longer lens counterparts on the other cameras).
- I also have a hunch that the camera does not have an OLPF. Or, if it does, it is very, very, very, very mild. The camera natively produces sharper images than the default files of the Alexa, or the Epic. (And the Epic is down sampled from 5k). The sharpness of the Alexa and Epic can be adjusted using the post tools provided by each company. (ArriRAW Converter & Red Cine X Pro)
- Some kind of diffusion is needed when filming talent to make the image more pleasing and forgiving.
- The "overly sharp" images may also be contribute to a "video" look if not addressed.

When shooting on the Epic:
- I feel comfortable underexposing the image at EI 800.
- At EI 1600, and 3200, the results of the underexposed images are unacceptable and I don't think that they are salvageable.
- Stay away from low color temperature light sources when shooting with the Epic; it only exacerbates the color science of the Epic. (Better colors and less noise comes from the light sources closer to 5,000k).

Downloadable RAW Frames (93MB): SLIR-LowLightTest.zip

What do you think? Do these results surprise you? Have you experimented with low light or underexposed images? Have you noticed the overly "sharp" look that the Blackmagic produces?

Until Next Time - Get Out There And Shoot!
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