White Balance clarification

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DanHD

Well-known member
I think I understand white balance now and how it correlates with lighting temp.

I just need some simply clarification from more experienced users. after the research I did I wrote a little summary of what I've learned, I just want to know it's correct.


Soo, here i go,

We white balance because the camera has to adjust the color spectrum for either orange/amber light or blue light, which are the prevailing lighting temeratures of indoor/outdoor. You cannot white balance for both. You balance for one at the expense of tweaking the color temperature of the other. THAT'S why we use lights with these two basic temeratures, so we avoid mixed lighting and can balance for 3200k or 5600k without making the other lights any more artificially blue or orange in hue.


...am I right? help
 
Not bad.

A big reason for white balancing (or choosing the correct film stock)
is that human vision automatically white balances, but cameras can't.

Working with EITHER 3200K OR 5600K simplifies lighting.
However, reality is not always so simple. If you put a light on a dimmer,
it will get "warmer" (lower color temperature). Same thing happens
to the sun when it gets late. In fact, if you're shooting shots at dusk,
the color temperature can change constantly.

Doing a white balance (or at least shooting a grey card for fixing it in post)
means that you are dealing with all those little variations.

Those little variations are why you can buy CTO and CTB filters in different strengths.

Here's another example: if you are shooting an interior day-for-night,
you might want to put lots of ND and CTB filters on the windows
and use 5600K interior lights, but adding a normal incandescent lamp
on the set might provide a useful contrast to emulate real nighttime conditions.
 
Thank you for your advise, man.

It's funny you brought up the day for night thing. I'm shooting a feature over winter where the director wants to shoot day for night in a hotel room.
Why such a drastic change in lighting when shooting that way?

I'm not sure i follow. Is this so when darkening the image in post, it will look blue like moonlight?

i mean, when using 5600k lights, the white balance will add tons or orange and red to balance it out, so I dont get it
 
DanHD said:
Thank you for your advise, man.

It's funny you brought up the day for night thing. I'm shooting a feature over winter where the director wants to shoot day for night in a hotel room.
Why such a drastic change in lighting when shooting that way?

I'm not sure i follow. Is this so when darkening the image in post, it will look blue like moonlight?

i mean, when using 5600k lights, the white balance will add tons or orange and red to balance it out, so I dont get it
Click to expand...

Day for night is a process that goes far beyond just messing with white balance. If you are shooting day for night and you want that "moonlight" blue in the lighting you will have use the right gels to get the color of moonlight you want. Some people use CTB gels to bring down the color temperature of a light to a more bluish color while others will go ahead and use theatrical gels that give them the blue color they want.

Generally when you are shooting day for night you have to be careful because hte process involves a lot of factors. I would certainly look into it but it isn't in the scope of this thread. For a good example of interesting outdoor day for night look at Pan's Labyrinth.
 
So what type of film do you use for day for night? daylight balanced or indoor balanced?
 
DanHD said:
We white balance because the camera has to adjust the color spectrum for either orange/amber light or blue light, which are the prevailing lighting temeratures of indoor/outdoor. You cannot white balance for both. You balance for one at the expense of tweaking the color temperature of the other. THAT'S why we use lights with these two basic temeratures, so we avoid mixed lighting and can balance for 3200k or 5600k without making the other lights any more artificially blue or orange in hue.


...am I right? help
Click to expand...

I think you get it, but to split hairs this might be a little better:

"
We white balance because the camera has to calibrate to the temperature of the lights we are shooting under.

The most common lighting temperatures are indoor (3600k) & outdoor (5600k). You cannot white balance (calibrate) for both temps at the same time. When you balance for one, the camera isn't calibrated for the other & colors will not be true to life.

For instance, if you white balance a sheet of paper inside (3600K) and go outside (5600K), the white paper (& the entire surrounding envoirnment) will appear more blue. Whitebalance outside (5600K) & the white paper will appear more orange inside (3600K).

THAT'S why we use lights with these two basic temeratures. We avoid mixed lighting to make sure the colors of objects are represented accurately.
"

More advanced...

"
If you are in an envoirnment where there is mixed lighting, it is possible to mix the color temperatures by white balancing on an object that is being lit by both lighting sources.

If you calibrate your camera to 4400K, the objects lit from the outside will appear slighty blue, the objects lit from the inside will appear slightly orange & the objects lit by both will appear normal.
"

And when you want to pwn white balance...

"
To create a 'mood' (warm/cold) you can use white balance to shift the color temp in the camera w/o using color filters on the camera. This can be done by white balancing under one lighting source & shooting under another one, or by white balancing on an object that is NOT perfectly white.

For instance, if you white balance on a very light blue object, the camera will subtract some blue from the picture & make the picture more orange. (NOTE, how well this works depends on how the camera you use & the object you try to white balace on. If the camera can't white balance on an object it will usually produce an error.)
"

let me know if this helps, if it makes it worse, or if you'd like to know more
 
DanHD said:
So what type of film do you use for day for night? daylight balanced or indoor balanced?
Click to expand...

if you are shooting inside day for night is easy, just don't show any windows.

otherwise...

white balance to the lights inside (probably 3200K)

block all light coming in from the window (more or less make a box / drop cloths that cut out the day light) draw the blinds & put a light outside the window. then put a CTO on the light and have it shine through the blinds

depending on the gel & bulbs, you should go from a color temp of about 3200K to 2200K. 2200K is around the color temp of most street lights & should make the scene look like it is dark outside.
 
zijital said:
if you are shooting inside day for night
... 2200K is around the color temp of most street lights & should make the scene look like it is dark outside.
Click to expand...
i guess that would depend on the type of streetlight. Sodium is quite orange;
mercury blue.

The moon is a special case, because it's a fairly true reflection of sunlight,
so it is about 5600K. It's also single distant source, so the shadows tend
to be sharp. For that reason shooting with sunlight can work.
if there is light coming through windows, then you need to cover the entire
window with ND and CTB filters.

Even when there is no moon, using bluer overall light (for example,
white balancing to a warm card) can work as a convention for night.

i was actually suggesting using a little table lamp for some local color temp
variation. It makes the shadows seem even bluer and darker, suggesting night time.

....and with an HVX, it's nice to have the extra light! :)
 
Thanks alot you guys. My knowledge is growing and I think I completely understand this now. It comes down to the fact that your eye can adjust for various lighting temps, but the camera simply cannot. So you balance for one or the other.

Awesome!
 
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