Strange WB results
 

Based on a suggestion from another member of this forum (Serena) I bought a set of Kodak 18% grey cards and I just tried a manual WB with my EX1. Something does not make sense.

The grey card read 4500K. Flipped the card over to the white side and press WB again and it reads 4000K. Closing the iris so the white card reads 50% and the CT reading is still around 4000K.

Unless I've missed something about the theory here the 18% cards are neutral grey and should give the exact same CT value as a white card. The spectral response graphs Kodak supply with the cards show close but not perfect tracking between the grey and white sides of the card, most markedly at the shorter wavelengths. Also Kodak suggest using the white side of the card for setting WB for video cameras.

Interested to hear any thoughts on this. When I have some time I'll try this under tungsten light. Not a big issue as the visual difference between 4000K and 4500K is pretty minor.

People on this forum expect way too much from those white balance #'s. They are just rough approximations . Likewise I'm not surprised that the color balance of a white surface and a grey one are different. Try comparing 2 ND filters.

Well, Bob has bought new Kodak cards which are made to a spec and that specifies very close spectral response from the grey and white surfaces. Bob's query has driven me out to check my cards, which are not new. In today's sunshine I got near identical WB on each side of the card (5100 & 5000), although my CT meter claims 4000 for the sunshine. We are in mid autumn with a diffusing clear sky (46S) and this isn't inconsistent with photo tables written for summer seasons, but maybe my elderly meter needs re-calibration (replacement doesn't seem worthwhile in the video age). There is a big difference using white printer paper for WB, this reading about 7000 on the camera and meter (the stuff fluoresces). My grey card is influenced a little by angle of reflection, so I was careful in setting normal to the lens axis. Also I set both to 50% brightness on the EX1 "meter".
Shooting a test card the colour balance looks right on vectorscope.

Serena,
thanks for checking that for me. I'll conduct some more controlled tests, I was using the somewhat dodgy fluro lights in my office and I didn't consider that changing the angle of the card to the various light sources could make a differnece, duh!

Good point about the average piece of 'white' paper too. That's what I'd been using and after you jogged my memory about grey cards I thought I'd get a new set. My old ones faded away with my 35mm still camera, sigh.

Strange that more of us don't use grey cards. DSC labs had every chart under the sun for sale at NAB but didn't bring any grey cards. Seems I'm one of the few people to ask for one. Thankfully the Kodak ones are a heck of a lot cheaper than DSC's.

I consider my purchase of the Vortex Media warm cards one of my smartest moves in obtaining a rich, warm look, particularly in interviews. They are not cheap, but then we are professionals are we not? We should have the best tools available, and I consider warm cards a must.
Vortex Media: VIDEO & PHOTO Tools and Training
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Sorry to be a curmudgeon about this subject, but all this discussion about the right card to use and buying a set of warm cards to bring on location so you can get exactly the right white balance seems to me both excessive and in the case of warm cards expensive. BTW - I do think getting a good (rich) white balance is important and worth taking whatever time is available.)

First, the best thing you can do to guarantee good color is a decent monitor. You can then adjust your color either by cheating your white balance or using in camera profile adjustments which are very fast and powerful on an EX-1.

Secondly, every professional cameraman I know carries around a 2" square gel swatchbook with 1/8- full CTO, CTB, and Minus Green gels available in seconds. You can use it on a piece of paper, a white napkin or whatever else is available and you can quickly dial in your white balance. (It does help to get used to seeing the difference between different white paper or sources.) Warm cards are simply copying this decades old practice.

Moreover in 25 years of video shooting I find that I routinely choose a combination of light CTB and minus green for my white balance - not currently available in warm cards. (That same combo can be preset into the EX-1 white balance function BTW)

There's nothing wrong with them, and I guess you can say they are more reliable than using different gels and different white cards all the time, but white balance is affected by so many issues - mixed light, the age of your bulbs, diffusion material, the angle of the card etc, that trying to be exact about the card itself seems misdirected to me. Usually you quickly cycle through a number of choices till you find something close. That and a decent monitor is all you need.

(Of course, if you have an engineer, scopes and a remote camera control, they'll pull out an expensive chart but then dial it in to taste anyway.)

Lenny Levy

I shoot everything neutral and do any color adjustments in post. It's a lot more controllable.

It's sometimes harder to undo a color shift in post.

It's a matter of opinion of course, but Hollywood sound mixers do adjust audio equalization as they record, and thousands of DP's worldwide use warm cards to get the best appearance on location ... I use warm cards, Tiffen filters, and other tools as I shoot. That's just me . . .

That's also a valid approach. DP's often want to achieve a "look" that a colorist probably wouldn't have in mind unless he were on set. That's a true artist at work. And a gradient filter can do things which are sometimes impossible in post.

Whatever is working for you is of course the best method and I don't mean to be a jerk about it, just that there are many ways to get a similar effect.

Dean if you are doing your own post or trust your colorist then neutral is fine. I don't generally do either.

Leonard...

I'm my own colorist because this company is so small there's no one else available to do it. :-)

The one advantage of doing it all is understanding the potential pitfalls of the entire process, and knowing where one can (and can't) take shortcuts during production.

Count your blessings. The rest of us are at the mercy of people who don't have time or the eyes to care as much as we would.

Lots of different views on this ... I am basically an editor. I love the editing process, and have been doing it longer than some people in here have been alive (35 years). I edited film most of my career, having gotten into video editing only about 12 years ago. Since I am a one-man band, I do it all because I finance my projects with 'grocery money' and cannot afford to hire writers, cameramen, etc. I just find that I try to accomplish as much on location as I possibly can, including lighting, WB, etc. I am currently producing an extensive documentary in which I have already interviewed over 70 people, all indepth interviews, and all interior lighting. The warm cards have paid for themselves many times over, just on this one project alone. I also highly recommend the Chimera window patterns. They have saved my butt in many empty hotel banquet room settings. CHIMERA Window Patterns

Good luck to all of you, and your views on filmmaking. And remember, there are no stupid questions.

I bought and I tested the gray card NOVOFLEX, measuring the difference of gray and white is 150-200k is very good quality.

While I've never trusted my Kodak grey card from the start, it did measure up to a calibrated WhiBal grey card. I searched the Kodak site for specs on the grey and white cards. While they do list their cards as neutral grey, I don't see any manufacturing numbers. Paper ages easily with light exposure, and I wouldn't be surprised if one side aged faster than the other. Just leave a newspaper out in the sunshine for a day and compare it to a copy that didn't receive the sun exposure. I'd put my trust in plastic (Whibal) over paper for white balance.

can somebody explain the the function warm cards to me? My understanding is it offsets the white balance to warm up the colors of your shot. Cant your just do this with your picture profile settings though? What is the advantage (if any)using cards as opposed to offsetting the WB with PP? Does it make the process easier or somehow different with cards?

Perhaps due too the fact that grayscale charts are preferable to gray cards. You can white balance on a grayscale.


Indubitably! Hence the question bears asking when the last time was that you saw an engineer use a white card? As I like to say, white cards are the worst way to balance a camera!! And warm cards are a much more worser way!!! Details and disclaimers :-) in a fun and wacky post! --->http://www.dvinfo.net/conf/sony-xdca...ml#post1077884

Do I have a warm card you ask?! But of course I do!! I also have a knife to cut my seat belt in case my car crash dives into the river! :~)


May I presume you refer to the low budget independent world? When there is enough money on the line, the majority of DPs use a DIT. Never (never say never) a white card or warm card.


Positively, any light source will degrade test charts, along with temperature and humidity. Most markedly unlaminated paper and cardboard charts are especially vulnerable on top of their weakness towards surface damage.

The absence of control numbers, "manufacturing numbers" as you put it, is further clue to an error prone chart.

Forgive me if I'm wrong but I thought grey cards were to measure exposure and white cards were for white balance.

Tradtionally, calibrated gray cards (usually Kodak 18% cards) have been used by still photographers to set exposure, but they can also be used to set white balance -- as long as they are truly color neutral. As far as color is concerned, there is no difference between a gray card and a white card.

In my opinion, there are several reasons why using WarmCards is better than adjusting the Picture Profile or other methods of warming the picture.

First, WarmCards save time. To set a proper white balance, you MUST manually white balance the camera at the location where you’re shooting. If you only use a plain white card, then you also have to take the time to manually adjust the PP to warm-up or cool-down the image. But, with WarmCards, all you have to do is aim the camera at the card, press the WB button, and you’re ready to shoot immediately.

Of course, you might decide to use the WB Offset feature of the camera to warm-up the white balance 100% of the time whenever you’re using a certain PP, but that doesn’t allow you much control on a shot-by-shot basis. And if you forget that WB Offset is activated, you may shoot video with a white balance you didn’t intend.

Second, WarmCards are designed to do more than just boost the overall Kelvin temperature. The four shades of WarmCards were chosen to emphasize the hues that make skin tones look best. Think of it this way: Using the Picture Profile menu to crudely make the whole picture warmer is like only having a Bass or Treble knob on an audio system. On the other hand, using WarmCards is like applying a pre-set Equalizer setting across the whole spectrum of colors. In most instances, especially when shooting interviews, the effect you get from WarmCards is noticeably more pleasing than just cranking up the color temperature.

Third, there’s no guess work involved. The effect that WarmCards provide is predictable, repeatable, and consistent. Once you’ve experimented with WarmCards and see the effect they have, you’ll have no qualms about using WarmCards without even checking a monitor.

Fourth, with WarmCards there’s no labor-intensive color correcting footage in post or waiting for time-consuming rendering to finish. And what if you have to give (or show) the raw footage to a client? Can you count on them to process the footage so it looks the way you intended it?

Fifth, WarmCards includes a Minus Green card for getting a cleaner white balance under common fluorescent lighting. There’s no easy way to do that by changing the Picture Profile

If you want more information about WarmCards, there’s plenty more details on Vortex Media’s website.
WarmCards - White Balance Reference System

Nobody uses WarmCards? There's over 24,000 crews using Warmcards.


NFL Films, CBS Sunday Morning News, 60 Minutes, 2002 Winter Olympics, 2004 Summer Olympics, 2006 Winter Olympics, 2008 Summer Olympics, 20/20, Dateline, E! True Hollywood Story, Survivor, Big Brother, A&E Biography, A&E Investigative Reports, HGTV, TLC, Larry King Live, Court TV, Discovery Channel, "CBS "Early Show", "Modern Marvels", A&E "American Justice", NASCAR Images, CNN, Good Morning America, Univision, Fox News Sunday, ABC World News Tonight, ESPN2 "RPM 2NIGHT", Sundance Channel, Fox Broadcasting, Entertainment Tonight, Access Hollywood, etc.

See a few of the rest --
Vortex Media: VIDEO & PHOTO Tools and Training

Okay, so maybe an ASC cinematographer working on a multi-million dollar feature film wouldn't use WarmCards, but how many of us are working in that world? Not me.

Wazzup Doug?

That is the mother of all testimonial lists. Why isn't my name in there! The warm card we have isn't yours actually. Would like to try yours someday. Certain manufacturing steps I've wondered about maybe you can clear up.

Didn't say nobody uses warm cards. The response was to Brian's statement that...

Well intentioned statement but not accurate. We know, a "DP" and an ENG camera operator are not one and the same. As I pointed out in the other thread, linked in my post above.. "White balance question", ENG and quick fix situations are mainly what you made the warm cards for, didn't you?

Since video became DIGITAL all of a sudden the number of "DPs" in the industry jumped exponentially. The "Lighting Cameraman" of yesterday along with everybody who bought a sub-$10k DV camera was now a self-proclaimed "DP". Nothing is set in stone... albeit I think it's safe to say most bonafide DPs do not use warm cards, or white cards. I'm talking at the NON-ENG Varicam, F900 and above level. Hate to resort to model #s but there you go. I believe the warmcard application should be specified, not described as an across the board panacea save ASC cinematographers! :-)

More thoroughly, it's safe to say a studio shoot, truck shoot and practically all network episodic television or any other location shoot usually employing a video village is probably not using warm cards. Any truck engineer I know of spotted pulling out warm cards to match cameras would never be hired again. Correct me if I'm wrong but you didn't design warm cards to be used by these people. You had in mind first the ENG shooter and, at a stretch, the EFP crew with no DIT. In the other thread linked in above post I also expressed it's not bad to have in the tool bag for these guys.

Still when someone says they want "the best white balance" and white or warm cards enter the discussion this understanding should be attached. They do have a place but it is not as a tool used to create "the best white balance". This statement is rooted in elementary camera engineering --- a realm the warm cards are not intended to be in. I suspect you agree.

On another note that list of customers is quite the impressive monster! How do you attain such specific records of all these shows and clients? I was curious of a few things. The before after shots are simulated or actual video grabs using warmcards? Forgive all the questions but here's some more. How did you determine the right shade for each warm card. What's the life expectancy before the dyes destabilize. Is there a QC process and tolerance range each card is tested for using a spectraphotometer. Can you specify this tolerance range if there is one.

All the honest reference white/gray card manufacturers I know of acknowledge the greatest challenge to producing reference cards to be consistent neutrality from card to card. Michael Tapes whose Whibal product gets mentioned here at times went so far to make videos about the topic WhiBal White Balance Gray Card Video Tutorial by Michael Tapes. I know your products are different and personally I do not agree with several of Michael's methodologies but he gets points for attempting some conformity to neutral readings. We both know this is a relevant matter. There are so many of these cards in the market as you know and the bulk of them are not close enough to neutral. Nevertheless they are blindly trusted because people are cameramen not camera engineers. Obviously the essential value of a premium white balance card is neutrality of the material. Your warmcards are also subject to spectral response when part of the sell is to match different camera crews. If customers are not made aware of these specs for such products they might as well carry different shades of laminated copy paper with them to balance.

Not true, the reflectance curve of a white card is not the same as a gray card.

Before buying them let me touch on one point I'm not thrilled with being the matte surface on vortex warmcards. One look at the array of competing products shows you're not alone in matting your test charts. But the truth is matting actually increases reflections and reduces dynamic range. The idea that it reduces reflections is a complete myth propagated by the old test chart manufacturers. Going back to the theme here of accuracy sacrificed for practicality, when the clock is ticking and its down to the wire yes I can comprehend how a matte surface is quicker to balance to because you don't have to fiddle with angling the the card.

Anyway in the end sometimes I don't white balance at all because it's not creative. Instead I like to be surprised by what I get just turning the camera on and if it looks bad there must be a reason for it in the universe which I just don't understand yet.

Max, you do know which forum you're posting on, right? Just in case you forgot, this is the XDCAM EX forum which caters to ENG/EFP cameramen who typically work alone or with a very small crew.

I'm not interested in getting into a debate about white balancing methods that are totally impractical at the level most of us work at, or trying to convince you that a lot of us have earned the title "DP" even if you don't think we deserve it.

I'm satisfied to let my previous posts speak for me, and leave it at that.

I thought this forum catered to all XDCAM EX users.
Certainly I've not noticed a significant quantity of ENG/EFP shooters here. There's a lot using 35mm adaptors and I doubt they're shooting ENG/EFP.