If you've been using a newer large sensor digital cinema camera, you may have noticed that your image takes on more reddish tones when using increased neutral density filtration. This is related to the way many of these ND filters block visible light, but let in more infrared light which can pollute the image. We've seen a few examples showing what IR pollution can do, and today, we have a video comparing RAW cameras, specifically the Blackmagic Cinema Camera, Arri Alexa, and RED EPIC, and how each of them handles black cloth when using IR cut filters of different strengths along with increased ND filtration.
This is a guest post by Cinematographer Ryan E. Walters.
I recently spent a day testing and comparing the Arri Alexa, Blackmagic Cinema Camera, and the RED EPIC. My goal for these tests was to explore how each of these cameras handles real world shooting environments. It was not to determine winners and losers. If you are of the opinion that there is only one great camera out there, then this series of tests is not for you. If, on the other hand, you are open-minded enough to get past the camera hype, and you want to know how these cameras respond, then I invite you to keep on reading. (I have also made the RAW files available for download).
Part 01 explores how each of the cameras handles IR contamination as ND is increased and how the Schneider IR Tuner Kit works with these cameras. Part 02 examines low light performance in order to evaluate noise levels. And part 03 takes a look at a high dynamic range scene to see how these cameras handle overexposure, skin tones, as well as how diffusion filtration affects the final image. I will be publishing part 02 next week, and part 03 the following week. (It is taking me a considerable amount of time to evaluate these images and publish the results. Believe me, if I could have had it all done this week, I would have ...).
I'd like to thank the following people & companies that made this series of tests 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)
Here is the overhead diagram showing how I lit part 01:
And here is a 10 minute video I produced to walk you through the results. A summary and links to the downloadable RAW files are below.
Observations & Recommendations:
- Use natural fibers in wardrobe and set dressing (like Cotton).
- Stay away from blends, especially if they have Rayon.
When shooting on the Alexa:
- For color critical applications, IR filtration is needed at all strengths of ND.
- For color critical work a different IR filtration system will be needed at 1.2 ND and above.
- For non-color critical applications, IR protection is needed at 0.9 ND and above.
- From the Tuner Kit, the 680 works the best.
When shooting on the Blackmagic:
- Need IR filtration at all strengths of ND.
- IR pollution becomes very noticeable at 0.6 ND.
- If IR filtration is used any remaining pollution can be graded out of the image.
- If IR needs to be completely eliminated in camera, then a different IR filtration system is needed.
- From the Tuner Kit, the 680 works the best.
When shooting on the EPIC:
- For color critical applications, IR filtration is needed at all strengths of ND.
- For non-color critical applications, IR protection is needed at 0.9 ND and above.
- From the Tuner Kit, the 680 works the best throughout the range, the 750 can be used up until an 0.9 ND.
Downloadable RAW Frames (396MB): SLIR-IRTest.zip
If you want to see additional filtration options and how they mix with other cameras, I recommend checking out Abel Cine's Expo.
What do you think? Do these results surprise you? Have you been using IR filtration on your camera, or is it an issue that doesn't concern you?
This post originally appeared on Ryan’s Blog.
Ryan E. Walters is an award-winning Oregon-based cinematographer. His work has allowed him the opportunity to travel worldwide in the pursuit of telling stories that are visually compelling. His experience includes feature films, documentaries, commercials, and shooting for Comcast, TLC, Oxygen, and the Discovery Channel.
