White balance

[DanHD]

So just to clarify (i'm still learning all this):

so im assuming from what ive learned here, depending on your white balance, if you're balancing for either daylight or interiors, the apparent color of 5600k or tungsten fixtures will also change?

So that's why you should stick with only one lighting temperature for each situation? (within reason)


and also, in a bedroom scene for example, you set up your tungsten key/fill lights ect, then white balance, is the camera going to shift the color spectrum to make the tungsten scene more blue?

Because in that situation maybe the light is shining on white surfaces and making them look a little bit more amber colored, in which case you might not WANT to make white look "white"



I guess my BASIC question is, does White Balance maintain the integrity of your lights temperatures? Or does it try to tweak them to be something theyre not

 

[j1clark@ucsd.edu]

I guess my BASIC question is, does White Balance maintain the integrity of your lights temperatures? Or does it try to tweak them to be something theyre not

We are not physicists. Hence, the goal in the case of correcting for 'color balance' is to make the scene match what the human eye does 'naturally', which is adapts to color shifts. We 'preceive' the wedding dress to be 'white'. If we were to get out our NBS traceable meter, we would note that the spectrum of the light reflected from that dress is X (for some value of X). Now the dress could be an 'off white' or whatever, but if we take a 'really' white card 'balance', then we would have an image of the dress + whatever cast there maybe, but that would match better the adaptive process of the human eye...

The problem of course is that camera's don't have the humanoid artificial intelligence (yet) to adapt automatically to match the 'human' response.... hence the need for a balancing process. That doesn't exactly match the human response but it eliminates the cast that is present in the light source.

There is also methods of introducting cast by balancing against 'whites' that contain a prescribed amount of color. Balancing against a 'bluish' white will result in 'warm' cast footage. This may be beneficial to the 'wedding' or 'documentary' film, since it may be difficult to spend the time in post-production (or not economic...) to put in a change of the light quality.

You can experiement to find out better the results.

 

[DanHD]

I understand that the camera needs to balance itself for certain casts of color, but still, i don't understand why we have different temperatures of light

is it only to match the prevailing indoor/outdoor standard temperatures?

Do you usually pick lights that match with the natural/practical light in the scene?

and if so, do you white balance before or after you setup your own lights

Because the whitebalance will see the tungsten lights and try to make them seem bluer than the eye sees them

or am I incorrect? does WB just give you the same perspective as the eye as far as color accuracy

 

[DanHD]

After doing some more research, I think I am starting to get it.

Correct me if I'm wrong.


Basically, the camera doesn't have the range to see white as "white" in the midst of a large dynamic range of light temperatures, thus you have to balance for one side of the spectrum (blue) or the other (amber/orange)
It's kind of like exposing for either the window or the interior, in a scene with large windows and darker interiors. The eye can instantly adjust and see detail in both, wheareas the camera cannot.

So, here I go, correct me if i'm wrong, buttttt
The reason we have lights with varying temperatures is to match the prevailing light temperature in the two most common shooting scenarios. interior, and day.


The reason we have white balance is so when using either one of those core temperatures, white will look white, and the camera will see what our eye sees


am I right??

 

[armisiano]

There are also different temperatues of light for the sake of creative controll. You may want a warmer light softly filling a face with a cooler edge light.

Sorry, don't mean to try and stir things up too much.

 

[pwyll]

DanHD: you are asking "can we all agree what WB is?"

Answer: Probably, if we wanted to take the time; research, study etc.

One thing is clear with even minimal research: It is not true to say that performing an EWB causes the camera to reliably reflect what we see. Go shoot a sunrise according to the "EWB every time the light changes" mantra. It will be tricky because you will have to recalibrate the camera every few seconds. Next day shoot the same sunrise and leave the cam on (tweaked) daylight preset, as described in my previous post.

Most people aren't concerned with theory. Most times this question arises from a more practical perspective: "Can we agree on how to use WB controls on my camera intelligently?" Answer: No.

You are going to drive yourself crazy if you try to reconcile all the advise you are getting. It's not just about right/wrong - the disagreements also reflect different perspectives, different priorities, different workflows, even different equipment.

 

[Sad Max]

Basically, the camera doesn't have the range to see white as "white" in the midst of a large dynamic range of light temperatures, thus you have to balance for one side of the spectrum (blue) or the other (amber/orange)

It's not an issue of 'range;' it's that the camera literally does not 'know' what 'white' is, until you tell it by white-balancing. When you frame up a white card and push the WB button, you are setting the camera to treat any surface with that chrominance and luminance as 'white,' and render all other colors the sensors pick up in relation to that 'white' standard that you have selected. Hence the variety of funky 'custom' looks you can create, by white-balancing on cards of differing shades and hues.

It's kind of like exposing for either the window or the interior, in a scene with large windows and darker interiors. The eye can instantly adjust and see detail in both, wheareas the camera cannot.

No, white-balancing is not analogous to exposure. The difference between window and interior (assuming there's no gelling) is that the color temperature of the daylight (bluish) differs from the color temperature of your interior lighting (most likely orange-yellow tungsten, if not some flavor of fluorescent).

The reason we have lights with varying temperatures is to match the prevailing light temperature in the two most common shooting scenarios. interior, and day.

Yes. Of course you can also use colored gels to make one light source match another; placing Tuff Blue filters over tungsten lights shifts their spectra toward daylight, and placing 84C Orange filters over a daylight source corrects the light toward tungsten.

Last weekend I shot a short for some folks who ignored my request for gels. Guess whose movie is going to come out bluish on one side of the frame, and properly color-balanced, on the other...

The reason we have white balance is so when using either one of those core temperatures, white will look white, and the camera will see what our eye sees

Basically, yes. Although 'closer approximation of what our eyes see' might be more accurate.

 

[DanHD]

What I was saying was that in a way its like exposure, in that the camera has a limited range compared to your eye

 

[DanHD]

DanHD: you are asking "can we all agree what WB is?"

Answer: Probably, if we wanted to take the time; research, study etc.

One thing is clear with even minimal research: It is not true to say that performing an EWB causes the camera to reliably reflect what we see. Go shoot a sunrise according to the "EWB every time the light changes" mantra. It will be tricky because you will have to recalibrate the camera every few seconds. Next day shoot the same sunrise and leave the cam on (tweaked) daylight preset, as described in my previous post.

Most people aren't concerned with theory. Most times this question arises from a more practical perspective: "Can we agree on how to use WB controls on my camera intelligently?" Answer: No.

You are going to drive yourself crazy if you try to reconcile all the advise you are getting. It's not just about right/wrong - the disagreements also reflect different perspectives, different priorities, different workflows, even different equipment.

I'm trying to make sense of what you're saying.
Tell me, how do you use white balance? It seems like all this advise is seemingly the same. The principles of color temerature, white balance, ect remain the same regardless of preference. I was concerned with that technical aspect of white balance,and what it does

 

[DanHD]

Guess whose movie is going to come out bluish on one side of the frame, and properly color-balanced, on the other...

Why was that? Because you were tungten balanced and the 5600k lights looked too blue?

 

[DanHD]

There are also different temperatues of light for the sake of creative controll. You may want a warmer light softly filling a face with a cooler edge light.

Sorry, don't mean to try and stir things up too much.

but the percieved temperature of light depends on white balance, does it not? so I guess to get a blue light in tungsten balance, you'd use a 5600k, with maybe oerhaps a CTB gel right?

 

[DanHD]

sorry for all the questions guys. These boards are where I get my education, basically.

 

[j1clark@ucsd.edu]

What I was saying was that in a way its like exposure, in that the camera has a limited range compared to your eye

The eye has a limited range, just that the eye does have an adaptive capability, and further, the human mind can 'impose' an understanding of elements in a scene.

You see a woman in a 'white' wedding dress, under a halogen lamp, you 'preceive' the dress as white. In fact if you close your eyes, get them slightly use to the 'dark', then quickly look at the same 'white' dress, you will preceive it as having a color cast.

Similar tricks can be done looking at a blue patch, then quickly looking away, and the 'blue' patch seems 'yellowish' until your eye/brain adapts...

Similar to persistence of vision that allows 'still' images to look like they are 'moving'...

When you select 'auto white balance', some engineer or group of engineers has developed something like 'your eye'. But the current methods are sort of a 'global' effect, that is all pixels in the frame are ajusted by the same amount.

If each RGB pixel group in a digitized frame where 'adjusted' individually, and 'automatically', then the fact that one has 'bluish' light from a window, and yellow/redish from the tungsten lights, would not matter, the pixels recording each region would be adjusted for that region's "color cast".

In still cameras, many people are shooting 'raw' images, that is as high a resolution, and bit depth an image as the camera is capable of, then in post production, using tools to adjust the relative color renditions to either remove 'color cast', or perhaps add it to effect.

Perhaps it gives the bride in the wedding dress a 'warmer' look to have a little 'yellow' in the image. Not too much... she spent an awful lot on the orthodontic work to have nice white pearly teeth (ever noticed this trend in modern movies, where not only stars have absolutely perfectly straight regular teeth, they now have brillian WHITE teeth...).

Unfortunately for most people working with digial film, the cameras and data acquisiton systems are not set up for say, 4K by 2K with 48 bits of resolution and saving all that 'real time' at full resolution.

Hence the need to at least get some form of adaption to the light, even if it is 'global', that is all pixels are corrected for the given 'white balance'.

 

[DanHD]

exactly. so your eye adjusts to make what you have learned as white appear white, yet the camera has no idea what the hell white is, so you have to literally hold up a piece of paper or a card and say "look this is white" and it adjusts it's color cast accordingly to make whatever is white adjust to a certain preset value of what white is, right?

I'm starting to get it.

So, since you want to try to avoid heavy amounts of mixed lighting in a scene, is it normal for the DP to CTO gel the windows to make sure there is no ultra blue color cast on the windows?

 

[Barry_Green]

Yes, exactly.

 

[Sad Max]

Why was that? Because you were tungten balanced and the 5600k lights looked too blue?

Exactly. Had I balanced for daylight, then the areas under tungsten light (which was most of the shot) would have looked very warm and orangey.

is it normal for the DP to CTO gel the windows to make sure there is no ultra blue color cast on the windows?

Yes. Although generally in my experience you'll consume less gel material matching your lights to a large window area, than vice-versa. Not that that's always a driving concern; most tv DPs with whom I work seem to prefer correcting large expanses of glass to tungsten, rather than gelling their lights to daylight. Maybe this has to do with the shift in light temperature over the course of a shooting day; I didn't think to ask.

 

[DanHD]

Will the interiors look natural when Balancing to daylight indoors?

I guess the only thing that would give it away would be a practical tungsten light somewhere on set.

When balancing for the windows on indoor stuff, do DP's completely avoid tungsten lights? within reason, I mean


If balancing for daylight indoors, and using daylights, using a daylight balanced film o white balance, would the color cast and "look" of white be basically the same as using all tungsten lamps and balance? I guess the camera would just adjust to make white appear "white" in either case so ultimately your image would look the same right?

 

[Sad Max]

Will the interiors look natural when Balancing to daylight indoors?

If you're lighting with daylight-temperature lights, yes.

I guess the only thing that would give it away would be a practical tungsten light somewhere on set.

Unless you filter that tungsten light, or use a daylight-spectrum bulb.

When balancing for the windows on indoor stuff, do DP's completely avoid tungsten lights? within reason, I mean

No need to avoid them if you can gel them, or put in daylight bulbs.

If balancing for daylight indoors, and using daylights, using a daylight balanced film o white balance, would the color cast and "look" of white be basically the same as using all tungsten lamps and balance?

In terms of color temperature, yes.

I guess the camera would just adjust to make white appear "white" in either case so ultimately your image would look the same right?

Again, in terms of color temperature, yes.

 

[Qzar]

Yes. Although generally in my experience you'll consume less gel material matching your lights to a large window area, than vice-versa. Not that that's always a driving concern; most tv DPs with whom I work seem to prefer correcting large expanses of glass to tungsten, rather than gelling their lights to daylight. Maybe this has to do with the shift in light temperature over the course of a shooting day; I didn't think to ask.

Gelling the window as opposed to the lights has several advantages. For one it helps lower the amount of light which gets through the window, which for daylight interiors in bright sunlight outside is always a good idea (most people will end up NDing the windows so they don't blow out anyway). Second, gelling tungsten all the way to match daylight really kills the light output of the light so you would have to get bigger lights which are hotter and use up more power. For professional DPs, gels are a minor expense in order to save a lot of trouble with lights.

 

[DanHD]

awesome feedback guys. I'm actually purchasing some .6 ND gels for an indoor shoot with huge windows right now...First time doin it. but hey, I'm a beginner, there are always firsts.