ProVideo Coalition.com: Stunning Good Looks by Art Adams

I’ve learned more about how cameras work by learning what the RED doesn’t do. But, with every software build, it does more. Build 20 looks to be the best yet… but it’s not perfect.

I shot these tests with Adam Wilt, at the Meets the Eye studios in San Carlos, CA. We shot two batches of over- and underexposure tests on one of their RED ONE cameras, first loaded with build 17 and then upgraded to build 20. I originally had planned to do a comparison of the two builds, but the scope of that article proved greater than my current workload will allow. Here I will focus strictly on build 20.

Yes, that’s me in my best “This is only for my drivers license, right?” pose. (I’m wearing a Sim Video shirt that I picked up at CineGear. I’m not endorsing them, even though they are an excellent company; it simply happened that I wore that shirt that day, and Adam insisted we have some flesh tone in the shot that wasn’t him. I hadn’t planned on being a model.)

The exposure that I read off the Kodak 18% gray card, with my Minolta Spotmeter F set at EI 320, determined our base exposure. The gray on the DSC Labs Chroma Du Monde chart is .5 stops brighter. The white chip on the chart is at 2 stops over the gray card exposure, and the black chip is approximately 5.2 stops under. (The card with black fabric squares is my new IR test chart, which did not play a role in this test.)

At the top left of the frame is an overlay of the waveform readout for that frame. I also zoomed in, using the Motion tab in Final Cut Pro, to frame only the DSC chart. When you see those zoomed-in frames please ignore the resolution trumpets as they are not accurate.

I didn’t include every exposure step as this article would not be finished until sometime just after Christmas. The frames that are shown are the ones that are pertinent to this exposure test. If you wish to see the entire build 20 test, please look for links to the Quicktime movies on the last page.

We shot tests under both tungsten light and daylight. The tungsten sources were two Lowell Totas, while the daylight sources were Kino Flo Image 80’s. The camera was set for RedSpace gamma, and I processed the clips in the latest version of RedCine that incorporates RED’s new build 20 color science. I used the Rec 709 color space in RedCine as RED has modified it considerably from previous builds, and also because the brightly saturated colors of Rec 709 are more likely to turn up any obvious problems or color shifts. The export gamma was RedSpace, which put black at around 10 IRE and white at about 80 IRE. (The RED never puts blacks at 0 IRE, requiring that they be pulled down during color correction.)

Personally I prefer the Camera RGB color space, but Rec 709 has always been RED’s weak spot and, as build 20 claims to make their Rec 709 implementation considerably better, it seemed appropriate to focus on it.

I white balanced once on the baseline exposure for each test and then applied that correction to all subsequent frames. We shot the tests in half stop increments with the goal of adjusting the EI in RedCine to bring the exposure back to normal. (For example, underexposing one stop on set would result in rating that clip at EI 640 in RedCine.) When I brought the footage into RedCine, however, I discovered that the EI ratings are in third stop increments. The half stop increments are pinned to the adjacent third-stop ISO rating that was the best eyeball match to the previous clip.

There are four tests: tungsten overexposure, tungsten underexposure, daylight overexposure and daylight underexposure. If you don’t like engineering details then skip to the last page for my exposure recommendations. Otherwise, turn the page for a look under build 20’s hood…

The Best of Stunning Good Looks

Art Adams | 08/30

A directory of my best articles, sorted by topic.

This entry is a guide to my best articles, sorted by topic. Enjoy!

NAB 2012: Assorted Snapshots

Adam Wilt | 05/08

A few cool things I saw at the show that didn’t fit into any other articles.

NAB is too big a show in too short a time to see more than a fraction of it. I’ve covered a few things in some depth (as have other PVC folks), but there’s plenty more that slips by without proper coverage. Here, I have a few photos…

NAB 2012: RED

Adam Wilt | 05/07

RED’s Ted Schilowitz discusses 2012’s products, and a photo gallery.

RED’s “Leader of the Rebellion” Ted Schilowitz held a press conference at NAB on Monday, describing the projects and products RED is working on. Rather than paraphrase him, I’ve got him on card (well, it’s not “on…

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Thanks, Art—really useful test!

How do you feel about setting exposure based on your spot meter at 320? Looking at your waveform captures at normal exposure, you hit about 40-45 IRE under daylight at 40IRE under tungsten. Could you open up 1/2 stop and bring grey closer to 50?

I ask because there’s been a lot of discussion in the past about where to rate the sensitivity of the RED, and even when I’ve used it and compared my light meters to the histograms on the camera, I’ve found it to be about 200 instead of 320, even when the camera’s set to 320.

Obviously, by setting 18% higher on the scale, you’ll get less over-exposure latitude and more under-exposure, but your mids might be more accurate.

What are your thoughts on this? I know there’s some debate as to where 18% grey should land on a waveform.

Great work writing this up—you make it look so easy!

Posted by Graham Futerfas on 08/15 at 04:43 PM

Great test Art! Been wanting to do one of these of my own since build 20 launched. I have noticed on quite a few non-scientific tests on my own camera the significance of the new build. I think color/kelvin is more accurate and the noise floor under tungsten light has had a significant increase in certain but not all footage. Its finally closer to a 9-10 stop DNR camera IMO as your tests show which RED and others boasted in the past but did not always prove true in real life shooting scenarios.
I feel most comfortable shooting between 250 and 320 ISO. That said, we rated the last feature I was on at 200 ISO. We were in a controlled interior environment and wanted to gain shadow latitude as we could control our highlights and the footage looks marvelous!
I have been experimenting in my own time shooting at 500-640 ISO on day exteriors to achieve greater overexposure latitude. If you expose correctly I have found the noise to be quite impressive in comparison to 320 ASA. Of course at the loss of some shadow latitude. But hey, first thing everyone does is crush the blacks in post anyhow Anyway, great stuff and thanks for the test results!

Posted by mikeburton on 08/15 at 05:06 PM

You’re most welcome, Mike. I agree with you that in most cases you’d want to cheat the ISO lower to reduce noise in the shadows, but 320 seems to be the point beyond which flesh tones and shadows get noticeably noisier, and very quickly, too.

I don’t like to play things so close to the edge, and in the past I’ve gone overboard to EI 160. I think I could do EI 200 (or 250 in a pinch) and feel pretty good about it, even in tungsten light.

What I’m discovering is that there’s a difference between pretty pictures and accurate pictures. The RED does pretty pictures, but not accurate ones. Unless you’re shooting food or fashion that’s probably not an issue.

There do seem to be a rash of fashion still photographers who think they can shoot with the RED and then pull perfect stills from it for print work, but they are completely high.

Posted by Art Adams on 08/15 at 07:48 PM

Hi Graham-

If you talk to serious video engineers they’ll typically tell you that middle gray is actually around 42 IRE, not 50, so in this case the RED seems to fall in the right spot—although that’s probably somewhat arbitrary when dealing with the RED. For example, in this case, outputting RedSpace gamma put all the picture info between about 10 and 80 IRE. I’m not sure what the other gamma settings will do.

I think you could shoot at EI 320 if you had to, but that’s a little too close to the edge for me. I don’t know that I’ve ever rated a 500 ASA film stock faster than 400, so my inclination would be to overexpose and push the noise floor down. I’m in the 200-250 camp, and it took these tests to convince me that I can back off from 160.

This article was anything but easy. I’m amazed I had the patience to finish it. The payoff was learning some very interesting stuff that they don’t tell you in the brochure.

Posted by Art Adams on 08/15 at 07:56 PM

“What’s odd here is that the red waveform seems to show that red is being detected in the column of color on the left side of the chart, where yellow and yellow-green appear. Those shouldn’t have any red in them at all.”

Au contraire—in additive RGB color, yellow is a mix of red and green. The RED’s red waveform is doing just what it ought to.

Posted by Adam Wilt on 08/15 at 08:05 PM

Aha! I feel an article correction coming on…

Posted by Art Adams on 08/15 at 08:21 PM

One questions.
WHen you talk about your EI are you talking about your lightmeter or RED´s ISO setting? DO they match in your tests?

Posted by .(JavaScript must be enabled to view this email address) on 08/15 at 08:22 PM

In the past I’ve left the camera set at EI 320 and then set my meter at EI 160 just to make sure I had enough lighting for an exposure. I’d then set the exposure by looking at all the telemetry in the viewfinder: zebras, histogram, raw data saturation sensor (barber pole), stop lights, etc. After having done this test I’d be curious to see how well I did by setting my meter and the camera to 200 and see how well the two lined up.

Posted by Art Adams on 08/15 at 08:59 PM

In the tests the camera remained set at 320, and Adam changed the exposure in .5 stop increments. I then compensated for that exposure change in RedCine by entering the appropriate ISO number (or, in the case of RedCine’s third stop increments vs. our half stop increments, to the nearest setting that matched the previous shot) and exported a ProRes HQ file with no further tweaking.

Red waveform mistake removed, blue waveform anomaly remains.

Posted by Art Adams on 08/15 at 09:02 PM

In the past with film cameras one was able to adjust the sensivity of the ‘sensor’ but the properties of the optical viewfinder was fixed. Nowadays it the otherway around. The properties of the sensor are fixed but the electric viewfinder is adjustable. For this reason digital cameras should not be tested like film cameras and this article creates bit a feeling as if cars are tested by driving them backwards.

The ISO setting does not affect the sensor and the gamma curve chosen in post has an effect to the level of mid grays. Consequently, IMO talking about overexposure is not that meaningful. Instead, one should exposure to the right. Red One gives the user a rather accurate idea where the clipping points of the channels really lie. For this one should set the raw view on and follow the histograms, trafic lights, and zebras to see what’s really going on. That’s how the last bits can be exploited and the distance to noise is maxmimized. More precisely, that’s the whole point of the raw view. Why would anybody want to underexposure unless one is forced to do so in lack of light?

Posted by .(JavaScript must be enabled to view this email address) on 08/16 at 01:27 PM

Art, RED Camera aside, I understand that tungsten’s typically run closer to 2900k than advertised 3200k but why are the daylight Kino’s so warm? Is it lamp age?

Posted by .(JavaScript must be enabled to view this email address) on 08/19 at 10:00 AM

Hi Art - Did you use any filtration in your tests? I would be curious as to how an IR cut filter would change these results. I have yet to shoot RED without either an IR cut filter or Pola filter and have had excellent results in color reproduction (build 17 though). My one color reproduction test with RED and no filtration was quite disappointing - hence my tendency to filter.

Posted by Red Razor Films on 08/23 at 10:57 AM

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RED Build 20 Torture Tests