Can I Use The Red Camera Ranger On A Gimbo
We tested how 2 of the virtually pop cameras friction match upwardly on exposure, noise, color fidelity and more than.
[Editor's Note: Contributors to this slice include Charlie Anderson, Alex Chinnici, Justin Derry, and Oren Soffer.]
Given all the buzz around RED'southward new Helium sensor, nosotros decided to put information technology to the test against one of its biggest competitors, the ARRI Alexa, in a diverseness of real-globe lighting set-ups in which we could push button both sensors to their limits and compare them at different extremes.
Note that this is a test specifically comparing the RED Epic-Westward camera with the new Helium sensor to the ARRI Alexa Mini with the Alev sensor. This is not meant to be a general "Crimson vs. ARRI" exam, every bit there are other configurations of RED'southward sensors that have been demonstrating very impressive dynamic range and paradigm quality results, including the Weapon Helium, and the Vista Vision Dragon, which we did not await at in this specific test.
Before we dive in, some technical info:
Tech stats
The ARRI Alexa Mini was shot in 3.4k Open Gate ARRIRaw style recording to C-fast cards, while the RED Epic-Due west Redcode Raw footage was shot at 8KHD with a 6:one compression. This was selected because it was the lowest possible compression nosotros could accomplish with the 240GB RED Mags we were recording to. It'southward worth mentioning that with the 1TB loftier speed Ruby Mags, information technology is possible to shoot 8KFF at six:1 compression on the Ballsy-W. The Epic-Due west was too equipped with the Standard OLPF for the purposes of this exam.
Unless noted on the clips, both cameras were set up to a color temperature of 4000K equally a mid-indicate between their ideal color temperatures, and were shot at ISO 800. In our testing, we found that the Helium'south native ISO was probably closer to ISO 1280, but decided to match both cameras to 800 for the ease of comparison. All footage was shot on 25mm, 35mm and 50mm Leica Summicron-C lenses, at varying T-stops. We utilized a diversity of units for lighting, including a pair of Digital Sputnik DS-1 heads every bit our main units, but as well incandescent bulbs, practical lamps, candles, and natural daylight.
For mail service, we performed a one-light form on the footage with Alan Gordon from Post Pro Gumbo; no secondary grades were performed. The Alexa footage was debayered into a Log-C gamma space and then graded based on a Rec709 LUT, with slight modifications. Alan noted the IPP2 and the Helium mail service-pipeline is still a work-in-progress, which makes it a flake difficult to compare to the Alexa, whose post pipeline has been tried and true and unchanged for many years now–but we still thought information technology would be pertinent to compare, every bit both cameras are currently on the market.
For the Helium footage, we used Ruby's new image processing pipeline, IPP2, and debayered the footage into a Log3G10 gamma space, which was then graded based on the IPP Preview 2 LUT. During testing, we discovered that the previous standard Log infinite for Ruby-red footage, RedLogFilm, was a much closer match to Log-C in terms of brightness and exposure. From our observations, Log3G10 didn't actually demonstrate a item advantage over RedLogFilm in terms of highlight retention, despite it being designed for that purpose. Instead, Log3G10 seems to just pull the overall exposure of the image downwards past most a half stop, and creates slightly smoother rolloff in the shoulder.
The Alexa has at least a stop and half more dynamic range in the highlights when compared to the Helium.
Despite this, we decided to stick to Cherry'south recommended workflow for Helium for the purposes of this test, while acknowledging that it is a work in progress. We should mention that nosotros edited and colored this footage a month later the kickoff version of IPP2 was released and a few weeks earlier the latest iteration of IPP2 came out.
Exam one: Overexposure and dynamic range in highlights
In our first exam, we wanted to button the sensors to the upper limit of their dynamic ranges, and see how much information could be retained in the highlights and brought back down to "neutral" exposure in the grade. We determined our "neutral" exposure of the field of study's face with our key light measured at an F/2.8 to exist at 60IRE, and graded the overexposed shots back down to match that value. In each subsequent shot, we increased the brightness of the key light by one stop, until we capped out at +5 stops overexposure from our base exposure (T/2 on the lens).
In the examination results, it is evident that the Alexa has at to the lowest degree a stop and one-half more dynamic range in the highlights when compared to the Helium. At 4 stops overexposure, the Alexa footage could exist graded back downward to 60IRE without losing any information in the highlight at all. At the same stop, the Helium footage begins to clip and lose data that cannot be retrieved or graded back to match. The cutoff is pretty sudden—at three stops overexposure, the Helium footage could still be perfectly matched to the base of operations exposure, but at four, the data is already lost. Notice the data loss in the bare bulb every bit well in the Helium footage compared the Alexa, which retains more particular in the filament.
At 5 stops overexposure, the Alexa footage begins to clip in the well-nigh overexposed regions of the subject'southward face. The Helium footage has total information loss in, and sharp falloff from, overexposed regions. The Alexa too seems to retain more than color detail in the overexposed regions, so when they are graded downwardly, the pare tone still maintains its color. In the overexposed regions of the Helium image, color information is lost, and the result when graded down is a very washed-out look.
Exam two: Underexposure and noise
In the second test, we set out to examine the cameras' performances at the opposite extreme: depression lite scenarios. Our subject was lit entirely with candlelight, his confront reading at 40 IRE at our "base of operations" exposure of T/two at ISO 400. The rest of the image was left to fall into darkness, except for a string of background lights. In each subsequent shot, we stopped down on the lens and increased the ISO to compensate for the exposure loss. Our goal was to track the noise level at increased ISOs as well as colour and image fidelity in underexposure.
In this comparison, it is articulate that the Helium is much cleaner at higher ISOs than the Alexa, but we found that the Alexa holds upwards surprisingly well and performed improve than nosotros expected. At 1600 ISO, the Alexa is withal relatively clean; at 3200, the noise flooring is obviously evident, especially when compared to the cleaner Helium image.
Interestingly, the Ruby-red image loses color particular when information technology is underexposed and re-balanced in the form, whereas the Alexa footage retains all of its color particular in the lower-mid tone range of the paradigm, even at higher ISO's. You lot can see in the comparison above that the color fidelity in the subject'southward face and the background of the scene changes from ISO 400 to ISO 3200 on the Helium sensor.
The visual and color details in the shadows on the Helium sensor seem to lose information sooner.
The rolloff into the shadows on the Alexa is more gradual as well; the visual and color details in the shadows on the Helium sensor seem to lose information sooner. From what we tin can tell, the Log3G10 gamma space clips data in the shadows. Therefore, when attempting to lift data out of the shadows in Log3G10, the information remains clipped, whereas Log-C on the Alexa re-interprets the data and is able to pull more than visual and colour detail out of the shadows when underexposure is "lifted" in the grade.
Test iii: Color fidelity
In this test, we set out to specifically check the color allegiance of the cameras and how closely they are able to lucifer to colors in reality. We lit a brightly saturated scene using our Digital Sputnik DS-1 heads and prepare our initial exposure at T/2 and ISO 800, and stopped downward incrementally to test color detail retention in underexposure. In the color grade, nosotros matched the green and magenta tones in the background across both cameras, and permit the other colors fall the manner the cameras interpreted them.
The first and nigh obvious divergence betwixt the images is how the two cameras translate the teal key light on the subject's face. The Alexa leans towards the greenish end of the spectrum, which results in a much greener shade of teal. The Ruby, on the other hand, has a magenta lean, which results in a much bluer-looking primal light.
A more subtle difference in interpretation between the cameras tin can be found in the color crimson: the Alexa has a lot more pinkish in its rendition of red, while the same colour on Helium leans a bit more than towards orange. Throughout our testing, we constitute that in general the Alexa Log-C to Rec709 LUT is far more ambitious with saturated colors than the IPP2 workflow, which favors more muted colors.
Test 4: "Natural" interiors
Nosotros wanted to set up a existent-world lighting scenario that DPs find ourselves in often: a naturalistic and contrasty interior with a vivid, over-exposed window, deep shadows, and mixed colour temperatures. We shot the exam on an clouded twenty-four hours then had to place a 1x1 LED panel merely exterior the window in order to create a blown-out hotspot on the curtains in the background. This light also flared the lens a piffling flake, which we decided to embrace, as it fit with our goal of creating a "real world" testing scenario, warts and all.
In the shadow regions, the Alexa manages to retain more information and visual detail.
The residue of the scene was lit solely with the practical lamp on the coffee table, and with no fill low-cal. Each subsequent shot was underexposed by a finish (our starting stop was a T/ii) and the ISO lifted in the form to compensate. We attempted to retain detail in the highlights equally much as possible while lifting the mid tones in the image to see if nosotros could discover a spot in which the window and the foreground were both properly exposed.
This exam served as a bang-up summary of all the differences between these cameras for united states of america. First, in the highlights, we found that the Alexa is able to retain more particular in the overexposed curtains than the Helium, and the rolloff is more than gradual. At two stops underexposure, the curtains (which metered at a 32, +viii stops overexposure from middle gray) retain full item on the Alexa, while they still testify some clipping on the Cherry. At three stops underexposure, both cameras are able to retain full detail in the defunction. The lamp on the java table is likewise clipping in our base exposure (T/2) shot in the Helium footage, whereas the Alexa shot retains all highlight detail in the lamp.
In the shadow regions, the Alexa also manages to retain more information and visual item, whereas the Helium clips information in the shadows. This is best demonstrated at the farthest extreme we tested—4 stops underexposure—where you can see in the comparison higher up that at that place is data loss in the cheeks and shadow regions of our subject's confront in the Helium footage. This tin can as well exist seen the darkest regions of the leather couch the subject is sitting on.
The Alexa footage has a green tint that differs greatly from the RED's interpretation of daylight, which is a lot cooler and more neutral.
In the overall image, the Alexa footage has a green tint that differs greatly from the RED'southward estimation of daylight, which is a lot cooler and more than neutral. The light emulating from the lamp is also a lot more than saturated in the Alexa footage and results in more warmth in the discipline'due south pare tone equally compared to the more than muted Helium footage. Finally, worthy of notation is how much cleaner the shadow regions are in the Helium footage compared to the Alexa footage.
Exam v: Available lite at nighttime
In our final test, nosotros took the cameras out at night to shoot some uncontrolled bachelor light and encounter how they interpreted some odd color temperatures that can be found on the street. Specifically, we wanted to come across how the cameras handled sodium and mercury vapor lamps differently. Similar to our colored lights test, we noticed that the sodium vapor spectrum leaned more towards yellow in the Blood-red footage, whereas on Alexa, it was a deeper orangish. Additionally, the mercury vapor lighting looks greener on the Alexa, while the RED interprets it as a little more than blue. Ultimately, nosotros found both interpretations of mercury and sodium vapor interesting in their own way and both cameras performed well in uncontrolled lighting environments at nighttime, with relatively clean images even at ISO 1600.
Terminal conclusions
All in all, we found this test quite illuminating. It reiterated things we knew from using these cameras in the field but also demonstrated many things we were surprised to larn about each of them.Namely, the Alexa has more latitude in the highlights (about ane.five stops more dynamic range than the Ruby) and is able to retain more colour detail through various degrees of over and nether exposure. The Reddish has less noise in higher ISOs than the Alexa, and past our estimation has a significantly improved color allegiance when compared to previous RED sensors.
That being said, both of these cameras create viable images and are at the acme of their technical game, and a preference of one over the other is purely subjective. Ultimately, they are but tools, and no 1 camera can substitute a DP's creative eye and taste for lighting and composition when information technology comes to creating a compelling image.
Feel free to draw your ain conclusions past downloading our test footage from both cameras, too as the stills from this article, at this link to our total resolution RAW files. Please note that in order to use the IPP2 Preview LUT, you need to select "Prove Avant-garde Controls" in Ruby Cine X. The LUT can be downloaded hither.
Source: https://nofilmschool.com/2017/02/shootout-arri-alexa-mini-vs-red-epic-w-helium
Posted by: davingoetted84.blogspot.com
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