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#1 Tim Schroeder

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Posted 13 November 2015 - 01:09 AM

I'm curious as to how DP's that work with film stock go about white balancing. Since the WB is fixed do they use gels on the lights set up? Or do they use filters in front of the lens to achieve the desired effect? If so, how incremental is the filtration?


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#2 David Mullen ASC

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Posted 13 November 2015 - 12:04 PM

Yes, yes, and/or they also can change it in the transfer for dailies or in the final color-correction.

 

Regarding gels on lights, first of all, the main reason you do that (other than for creative color effects) is to match them to the surrounding color temperature.  If they don't match, the playing with the white balance in post or in the camera with filters isn't going to fix that mismatch.

 

So if you are in a situation where there are no natural sources to match to, like in a stage set or a night interior, then odds are low that you are going to, let's say, put Full CTB (blue) gel on every tungsten lamp and then use daylight film stock -- you'd just use tungsten film stock.

 

As for using a Full Blue correction filter (80A) on the camera lens to correct tungsten light to daylight so you can use daylight stock, versus using Full Orange (85B) on the camera lens to correct daylight to tungsten so you can use tungsten stock, the second is more common because the blue filter loses 2-stops of light but the orange filter loses only a 2/3-stop of light.  

 

Hence why it is easier to use tungsten stocks outdoors in daylight where there is plenty of exposure for an orange correction filter but harder to use daylight stocks at night with a blue correction filter because generally light levels are lower.

 

So the most common scenario is to use daylight stock in daylight situations, or tungsten stock with an 85B filter, and then use tungsten stock in tungsten situations.  You could also use daylight-balanced lights and daylight stock.

 

But there are all sorts of variations possible. Some cinematographers use tungsten stock in daylight with only a partial correction, like an 81EF, for a cooler effect (you'd want to shoot a grey scale for dailies using the full correction so that it looked neutral in daylight and the scene that followed with the partial correction looked cooler in comparison to the grey scale).  And some use the partial correction in order to gain a little more exposure over an 85B filter (since there is barely a 1/3-stop difference between the 81EF and the 85B, you'd be more likely to use the LLD filter, which is mainly a super Skylight filter) and shoot the grey scale and scene under that same filter for a neutral balance.  And some just don't shoot with any orange correction and have it all timed to neutral -- film negative has enough color information to handle that.

 

And of course, some cinematographers use uncorrected tungsten stock in daylight for a blue effect (like for day-for-night work) and some use daylight stock in tungsten light for an orange look ("Backdraft" for example shot all of their big fire sequences on daylight stock so that the fire rendered more orange-red.)

 

I've played with color timing of dailies by using different filters when shooting the grey scale and then pulling the filter for the scene -- it's similar in video to white balancing using a pale colored card.  I've put a pale blue filter on the camera for the grey scale, or a pale blue gel on the light inside, and then pulled it for the scene and gotten a warm look because the timer had to add warmth to the image in order to get the grey scale to look neutral.

 

I always shoot a sign after the grey scale that says things like "COLOR: SLIGHT WARM GOLDEN TONE" or whatever.

 

Keep in mind that you normally don't look at a negative image, the negative has to be converted in same way into a positive image for viewing, so there is always a color-correction opportunity here to balance the image.  Without any grey scales or notes, a colorist is likely to just go for a neutral balance no matter how you shot the original, especially for outdoors footage.


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#3 Tim Schroeder

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Posted 15 November 2015 - 08:59 PM

Alright, if the goal is to match the color temp of the area, how do you find the exact color temperature so that you can use the correct filters to achieve the desired effect?
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#4 David Mullen ASC

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Posted 15 November 2015 - 09:08 PM

Are you asking about matching lights to the color temperature of the location?

 

As for matching the color temperature of the scene to the film stock, as I said, negative film has to go through a color-correction step to be viewed as a positive image, so that is one point where setting the color balance can take place, besides camera filters.  In other words, even if you use film stocks and filters to match the setting, you only have to get into the ballpark because the timing of dailies or the final project gives you the opportunity to get a neutral balance if that's what you want.

 

As for matching lights to the setting, you can use a color meter if you want to be precise, though the truth is that unless the location has artificial lighting with color spikes that are hard to see by eye, you can usually get close to matching a light to the location just with gels and your eyes and/or monitor (if shooting digitally.)  In other words, let's say you use an HMI in a day scene and it feels too blue compared to the natural ambience, you will add some degree of CTO gel to the HMI to get a closer match, and often if it matches to your eye, it is close enough for practical purposes.

 

You can find out the published MIRED shift of color correction gels and filters when you need to convert "x" color temperature to "y" color temperature, if you know those two values.


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#5 Tim Schroeder

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Posted 22 November 2015 - 12:00 PM

So in a nutshell, when shooting on film stock, if you get the color temp close enough it can easily be corrected in the DI process or through chemical means? And color temp is often correct through filters or a combination of lights and filter?
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#6 David Mullen ASC

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Posted 22 November 2015 - 12:33 PM

There are no "chemical" means of changing the color balance on the stock, unless you mean "photo-chemical" means, i.e. making a corrected print using RGB printer light adjustments.  But, yes, most people get the balance close and rely on the latitude of the negative stock to correct the image when later making the positive, whether that means a print or a transfer to video, or a color-correction of a scan.

 

As for correcting the lights, it all depends on whether you can correct every light, artificial and natural, because if you can't, then you'll have a mix of color temperatures.  You can't really correct a shot with mismatched colored lighting within the same frame and then correct it all to match each other later.  I mean, with digital post tricks, sometimes you can come close to fixing mismatches... but it is a lot of work and often only partially successful.

 

Plus there are practical issues -- let's say you have twenty lights and they all need the same correction gel.  Well, if they are the only lights illuminating the set, it would easier to just put one correction filter on the lens than to gel the twenty lights.  Or maybe it would be fine to just do that correction in post.  A common example is a scene shot in a supermarket at night under hundreds of greenish fluorescents -- if there are too many tubes to swap out, then you might have to add green to your extra lighting augmenting the overheads to match, and then you have the choice of using a magenta camera filter to cancel the overall green, or to correct out the green in post with color timing / color-correction.  The second option is very commonly done.


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#7 Patrick Cooper

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Posted 17 December 2015 - 12:02 PM

Generally, I find film more versatile with regards to handling different colour temperatures (within daylight) compared to digital. If you're shooting outdoors with digital and you want reasonably accurate colour rendition, you have to readjust the white balance if the shooting location / situation changes from full sun to shade to cloudy. If you have a daylight balanced film however, it will handle sunny conditions, shadow and overcast without any need for adjustment (unless you're going for a certain look - warmer / cooler etc).


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#8 David Mullen ASC

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Posted 17 December 2015 - 12:21 PM

Film sees the changes in color temp from sun to shade just as well as a digital camera does, it's just that with film, you have to have some sort of conversion step from negative to positive, either a print or a scan or a video transfer, and at that point, you can also color-correct for those differences.  But it is not correct that film somehow renders all of those different color temps throughout the day as one color and therefore needs no scene-to-scene correction later -- it is mainly that you are seeing those changes live on your digital camera and feel the need to then correct the color immediately since there will probably be no dailies step.

 

So if you were shooting a digital camera with a lot of color information, let's say 12-bit ProRes 4444 in Log-C on an Alexa, you could treat it like film and shoot all day at one daylight color temp setting and then fix the imbalances later if you have a colorist doing dailies.  Conversely you could shoot film, develop it, and make a one-light dailies transfer based on one grey scale at the head of the roll and not have those changes corrected out.

 

So I don't really see a difference in this case between film or digital, both see color temp variations throughout the day and both may need to be corrected for that if you want better matching.  The difference is mainly when and where you do that matching, in camera, in dailies, in the final color-correction.

 

Film has a bit more color richness to it but that only means it sees those changes throughout the day more clearly, not less clearly, so what you are really saying then is that the latitude of color negative makes it easier to fix those differences later in post, not that the latitude eliminates the need to make corrections in the first place.  Otherwise you'd be arguing that the advantage of film is that it is less sensitive to color variations.

 

Where there is a bigger difference is when you are shooting with a lower-end digital camera with poorer color information, less dynamic range, and more compression in the recording -- with that sort of camera, you may be happier to balance the color temps throughout the day pre-recording since you will have less latitude in post to color-correct.  Plus probably you aren't doing some sort of dailies color-correction anyway.


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#9 Patrick Cooper

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Posted 18 December 2015 - 04:33 AM

Very good points David. This might be going slightly off topic but when I do still photography, I find that daylight balanced slide films are generally pretty good at handling different colour temperatures under natural daylight illumination. Take Fuji Velvia for example - Ive photographed landscapes with that film stock in both sunny and overcast conditions. Yes there may be some colour temperature changes recorded by the film but to my eyes, the colours always look natural in either of those light conditions. I was wrong for mentioning shade in my previous post. I admit that daylight balanced films will render rather cool looking images in shade, requiring some kind of colour correction. But for sunny and overcast conditions, I'm more than happy with the results I get straight from the film - (from the exposed transparency.)


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#10 Mark Dunn

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Posted 18 December 2015 - 05:00 AM

I reckon that the difference is that you look at stills one at a time and in those few seconds the brain adapts, but a change of colour temperature is much more noticeable across a cut. 1/24 of a second isn't long enough to accommodate the change.

Having just scanned 5000 slides I think the differences are more noticeable.


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#11 Bill DiPietra

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Posted 18 December 2015 - 11:53 AM

Very good points David. This might be going slightly off topic but when I do still photography, I find that daylight balanced slide films are generally pretty good at handling different colour temperatures under natural daylight illumination. Take Fuji Velvia for example - Ive photographed landscapes with that film stock in both sunny and overcast conditions. Yes there may be some colour temperature changes recorded by the film but to my eyes, the colours always look natural in either of those light conditions. I was wrong for mentioning shade in my previous post. I admit that daylight balanced films will render rather cool looking images in shade, requiring some kind of colour correction. But for sunny and overcast conditions, I'm more than happy with the results I get straight from the film - (from the exposed transparency.)

 

Well, overcast situations can provide some lovely images.  As one teacher succinctly put it many years ago, an overcast day will give you much more saturated colors because the combination of the sun behind the clouds is creating one large, soft source.  Whereas a sunny day is entirely different.  So if you are photographing green trees on both days, you with notice a significant difference in "lightness."


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#12 John E Clark

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Posted 18 December 2015 - 01:38 PM

I reckon that the difference is that you look at stills one at a time and in those few seconds the brain adapts, but a change of colour temperature is much more noticeable across a cut. 1/24 of a second isn't long enough to accommodate the change.

Having just scanned 5000 slides I think the differences are more noticeable.

 

With slide film it probably does produce different effects... but with negative still film, one has to wonder if the printer has 'adjusted' the color balance behind the scenes.

 

I know I have some very 'bluish' slides for the few slides I ever shot, on those overcast days or 'northern' light shots.

 

For the wedding biz, the bride's white dress was the usual 'key' and would be a problem if the dress was actually an off white of some sort...

 

Then there was the time the Wife was shooting in Jerusalem at noon, under a 'muslin' canopy... there was a distinct, and somewhat unfortunately yellowish/brown cast... Since she was shooting digital by that time, it was a simple matter of getting an adjustment for one shot, and the a Photoshop macro for the rest in batch mode...


Edited by John E Clark, 18 December 2015 - 01:39 PM.

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#13 Tim Schroeder

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Posted 27 December 2015 - 12:55 AM

Film sees the changes in color temp from sun to shade just as well as a digital camera does, it's just that with film, you have to have some sort of conversion step from negative to positive, either a print or a scan or a video transfer, and at that point, you can also color-correct for those differences.  But it is not correct that film somehow renders all of those different color temps throughout the day as one color and therefore needs no scene-to-scene correction later -- it is mainly that you are seeing those changes live on your digital camera and feel the need to then correct the color immediately since there will probably be no dailies step.

 

So if you were shooting a digital camera with a lot of color information, let's say 12-bit ProRes 4444 in Log-C on an Alexa, you could treat it like film and shoot all day at one daylight color temp setting and then fix the imbalances later if you have a colorist doing dailies.  Conversely you could shoot film, develop it, and make a one-light dailies transfer based on one grey scale at the head of the roll and not have those changes corrected out.

 

So I don't really see a difference in this case between film or digital, both see color temp variations throughout the day and both may need to be corrected for that if you want better matching.  The difference is mainly when and where you do that matching, in camera, in dailies, in the final color-correction.

 

Film has a bit more color richness to it but that only means it sees those changes throughout the day more clearly, not less clearly, so what you are really saying then is that the latitude of color negative makes it easier to fix those differences later in post, not that the latitude eliminates the need to make corrections in the first place.  Otherwise you'd be arguing that the advantage of film is that it is less sensitive to color variations.

 

Where there is a bigger difference is when you are shooting with a lower-end digital camera with poorer color information, less dynamic range, and more compression in the recording -- with that sort of camera, you may be happier to balance the color temps throughout the day pre-recording since you will have less latitude in post to color-correct.  Plus probably you aren't doing some sort of dailies color-correction anyway.

 

 

So in the sense of lower end digital cameras with an 8 bit 4:2:0 signal (Say the a6000 for example) it's best to just have the color balance "on the money" as opposed to balancing it to capture the color of the location? Would it be a bad idea to shoot everything whilst maintaining a 5600k color balance?


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#14 David Mullen ASC

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Posted 27 December 2015 - 01:15 AM

It would be best to get the color you want in camera, whether that means with a color cast or neutral, just depends on the look you want, with the caveat that if you can achieve the color effects you want while working with the camera set to a higher color temperature, which may mean using daylight balanced lights or some degree of blue gels or blue filters, you'd end up with a cleaner blue channel.
Either way, if you can get the color and noise level to your satisfaction in the original so that minimal to no color-correction is required in post, you're going to have a better time if dealing with a very compressed recording with only 4:2:0 color information.
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#15 Bill DiPietra

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Posted 27 December 2015 - 10:42 AM

Either way, if you can get the color and noise level to your satisfaction in the original so that minimal to no color-correction is required in post, you're going to have a better time if dealing with a very compressed recording with only 4:2:0 color information.

 

Especially if you wind up working on a project where you are doing a lot of work with a post lab that charges by the hour.  The more you get right in-camera, the less time you will spend doing color correction and the more money you will save.


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#16 David Edward Keen

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Posted 15 March 2016 - 06:47 PM

Quoted: "(you'd want to shoot a grey scale for dailies using the full correction so that it looked neutral in daylight and the scene that followed with the partial correction looked cooler in comparison to the grey scale"

 

What is meant by "shooting a grey scale" ? I currently understand grey scale to be the brightness, from black to white. 


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#17 Stuart Brereton

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Posted 15 March 2016 - 07:23 PM

A grey scale often has a large area of 18% grey, in addition to the 'scale' from black to white. With film it is common practice to shoot a few seconds of the grey card at the head of each roll and/or scene in order to let the dailies timer know what your exposure and color intentions were .


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#18 Satsuki Murashige

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Posted 15 March 2016 - 09:29 PM

These are greyscale charts: http://dsclabs.com/d...balance-charts/

You can also just use a simple 18% grey card: http://motion.kodak....tm#graycardplus

http://www.bhphotovi...ard_8x10_1.html
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#19 Duca Simon Luchini

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Posted 24 June 2016 - 01:49 AM

Hi everybody,

I'd like to know, instead, how can you catch the real on location temperature. I mean: often it happens you are in a location (never mind if you are in an indoor outdoor set) where there is a great natural lighting.

Shortly, if you have to film without any lighting, catching "the magic light moment" of your location, how your camera can catch exactly or approximately the temperature lighting on set (and you can see with your eyes)? Many filmmaker have not  a color meter (costs at least $ 1,500...) how have you to set your white balance?

 

Thanks for a reply!


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#20 David Mullen ASC

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Posted 24 June 2016 - 10:17 AM

Well, if you are shooting digital, you can see the effect of your camera's white balance setting on the monitor.

 

If you are shooting film, you just decide if the color is daylight, tungsten, or in between.  Film has enough latitude that you can shoot tungsten film under daylight and correct it in post, or if you think the color is halfway to daylight, you can use a halfway correction filter like an 81EF instead of a full correction like the 85.  Again, you can correct the rest of the way in post.

 

In other words, it's not important that you "exactly" correct the color temperature in camera, you just have to get close enough that you can color-correct it later.

 

Plus, often for creative reasons, you don't want an exact match -- perhaps a scene in the deep shade of the forest feels cool to you so you don't want to actually match the color temperature, you want a setting that leaves some coldness to the light.  And often a sun set moment has very orange sunlight and most people don't want to match that color temperature exactly either and thus correct out the orange, they want to capture that orange color which means leaving the color temp of the camera or stock more at standard daylight 5600K.

 

Same goes for a warm candlelight scene -- you usually don't want to match that color temperature, you want the candlelight to feel warm, not neutral white.

 

Capturing the colors of natural light does not require a color temperature meter.  Color temperature meters are useful for measuring what you can't see with your own eyes, like how much green is in a fluorescent so you can use the correct gel on another light to match it to an existing light.


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