Last week, we took you through Day ISO tests, Dynamic Day Exterior range tests, Back Light/Skin Tone tests and Fill Light ratio tests with the Canon C500 and Arri Alexa. This week we have a whole new round of testing for your review. Let’s get this PARTY started!
This test is to find the exact level of Neutral Density where a camera starts to become polluted with IR (Infrared). When you use high levels of ND to take your exposure down to an f stop that will deliver more cinematic depth of field, the sensor picks up on IR and that IR contaminates your image with a reddish brown hue. This is very difficult to get out of your image even with the most powerful of color correction devices.
Each sensor has an IR filter but finding that IR filter’s breaking point is what this test is about. None of the camera manufacturers will readily disclose what their IR filter level is, so I compare this test to Indiana Jones’s expedition to find the Holy Grail.
We systematically did this test with Tiffen WW Straight ND filtration and quickly realized the limits of the Alexa’s IR filter. After a 1.2 ND, you really could see the IR pollution start to enter the blacks. What you are looking for is this reddish brown contamination. Look to the trees behind our model, over each shoulder.
On the flip side, Canon has really mastered this IR filter technology with the effort devoted to the still photography arm of their company. So even with eight stops of ND added, there is no IR pollution evident in any of the blacks.
Let’s look at some screen grabs of the side by side where it is very apparent when the Alexa starts its IR pollution and where the Canon remains clean.
I love this test, but please be prepared — because it is a long one. In-depth testing is what it is all about in finding your digital sensor’s voice. I broke it into two parts, Over Exposing and Under Exposing, to give you time to digest the information.
We start with the Alexa with the key light matching the exposure on the camera. If the light was at a 4.0, then the camera’s exposure was set to a 4.0. We slowly open up the lens in one third stop increments. The reason for this test is to see how the camera handles over exposure and whether it looks like video when it blows out or whether it looks like film. The Alexa across the board looked just like film. It over exposed so creamy and organically. I loved how this camera looked.
I thought the breaking point for the Alexa was at +4 and 1/3 stops. This is where the video clipping came in and it looked digital. It lost its filmic/organic look.
With the C500, this overexposing did not look organic or feel like film. At +2 and 1/3 stops over exposed, the faces of our models started to clip in a very digital way. It was not creamy. I felt this was one of the biggest limitations of this camera.
To conclude on this part of the test, the Alexa has 14 stops of latitude and the C500 has 12. The Alexa held the highlights two stops more than the C500.
I do the underexposing part of this test because I feel that digital sensors look better when they are starved of light. I used this technique with film. I under exposed most of my Kodak stocks -2/3 of a stop. When you start underexposing the image, it feels more filmic, to my taste. So with our Alexa, I felt that -2/3 to -1 stops looked really good as a base exposure. When I shot Need for Speed, I did the same.
With the C500, I found -2/3 to -1 stops under exposed was the right recipe as well. Both sensors acted very similarly in the under exposing tests. This exposure approach brought about a more organic and filmic nature.
Now, here is the side by side of these.
The Night ISO test was essential with all the night work on Need for Speed. I needed to be able to see how the digital sensors delivered the night. Looking at both cameras, the Alexa delivered a fairly balanced image with good skin tones and color. The night colors seemed to render in a very neutral way. The director, Scott Waugh, and I noticed right off the bat that the C500 came up right in the pocket that we had envisioned our nights should look.
We wanted that warm golden glow of the sodium vapor street lights that would become a character in all of the night races and chases. The C500 also seemed to energize the colors in the background. The subtle tones that were very neutral and mundane on the Arri Alexa flew off the screen on the C500. I feel that we could have dialed this look in on the Alexa fairly easily, but I knew from our skin tone test last week that some of the subtle color gradients that we were seeing in the background would be lost on the Alexa and both Scotty and I did not want that. The nights had to feel unique and contemporary. Our style of shooting was a throwback to the 70s, but we did not want our look to do so as well.
The other thing that we noticed was noise levels. On the 60’ screen, we matched the noise levels on the Arri Alexa at 1250 ISO to the noise levels of the C500 at 4000 ISO. What a big difference. That is another two stops for you to work with at night, which could enable a 500mm long lens or 120fps without changing any light levels or having to light to that level. This was the power that Scotty and I quickly realized. Imagine shooting with the available lights on the street, actually taking them down a notch because they were too bright, along with turning some off because we wanted a little more contrast. With all this, we still had enough light and ISO range to shoot 120fps. This was a game changer for us because it flipped the rules. Never before were you able to do this with available streetlights. The ISO range that we felt comfortable with on the Arri Alexa was 1250 and with the C500 our extreme edge ISO for a couple of shots would be 4000 ISO. These became our rules not to break.
Our comfort zone on the C500 would fall more in the 1600-2500 ISO because at 24fps, the night street balance of all the available lighting looked good there. We knew we could go there for a whole scene, not just a shot or two at 4000 ISO. I did shoot a whole sequence at 4000 ISO, the Drive In sequence in the movie. Be sure to check this out when the film is released in March of 2014.
Let’s look at the side by sides here.
I knew that we would be doing a ton of shots inside the cars with our actors physically driving and I wanted to make sure that by just adding a little dashboard fill light I could literally drive down our race route and not have to add a light. We tested the Arri Alexa in this configuration and noticed right away the physicality of the camera’s size was incredibly limiting. Yes, we had an Alexa M body ready to go, but I knew we could not afford more than one. The Alexa seemed a little ruddy in the blacks. Ruddy is a term I use for a dirtiness in the blacks that is hard to get out. When the C500 came on the screen, it seemed to see all the colors in a much brighter and more vibrant way. It energized the background.
Scotty loved this because he knew the way to sell speed at night is to actually see something moving by in the background on the sides of your frame. I knew that our schedule and budget was incredibly tight, which meant we needed to take advantage of as much lighting as the city of Macon, Georgia could provide us. We made the C500 our go to night camera based on these tests. It gave Scotty the freedom to have our actors drive without any lights out on the hood that would block their vision. This enabled us to link our actors with other actors driving as well.
Because we did not have lights all around the car, I could have my camera operators looking out the front windshield and pan right back to our actors driving. These shots are usually done during the day because you lack this ability to pan because of the lights. We were able to light over three miles of night street racing with about 12 lights. YES! It is possible. That was so great for our stunt drivers because they could really go at it and get the cars cranking through turns and not worry about running out of lighting real estate. This style of shooting action sequences as a play, like we did on Act of Valor with the SEALs hitting a target, was the right recipe again to put you, the audience, in the driver seat at speeds over 180mph.
In an upcoming post, we will take these two camera systems through action and speed photography and how each one handles this.
I would love to hear your comments on all of this. Please chime in with your thoughts and opinions because it is more beneficial for everyone in the education process. I take the time to answer every comment, so you are talking directly to me.
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