White balance with digital

Started Sep 28, 2005 | Discussions
karuzo Contributing Member • Posts: 506
White balance with digital

Hello all,

I am researching on architectural photography. I read in a book (film based) that sometimes it is required to expose the same picture multiple times when color temperature is mixed (tunsten, fluorescent, daylight) w/ color correction filters as necessary. In digital, as we know, there is the white balance. It is possible to take several shots with differnt balance settings (or shoot raw). What is the best way of mixing the result images in post process? Is it by using mask layers and carefully reveal, or is there a more efficient method?
Thanks,
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chris3010 Senior Member • Posts: 2,738
Gels and wb bracketing

You're right, the easiest way for light you can't change is to capture in different WB settings, then merge the images. Examples would be dusk photos (high color temp, blue sky) with tungsten interior (low color temp, yellow), when you want the window light to look less "blue".

For mixing interior lighting (e.g., tungsten, daylight, fluorescent) it's easier to use gels on the strobes when possible. Inevitably there is light mixing between different areas, and masking/merging is a pain-in-the-butt.

I use a combination of gels, multiiple exposures, and the realization that mixed lighting just looks better sometimes -- so don't try too hard to make all light look like 'daylight'.

Chris

karuzo wrote:

Hello all,
I am researching on architectural photography. I read in a book
(film based) that sometimes it is required to expose the same
picture multiple times when color temperature is mixed (tunsten,
fluorescent, daylight) w/ color correction filters as necessary. In
digital, as we know, there is the white balance. It is possible to
take several shots with differnt balance settings (or shoot raw).
What is the best way of mixing the result images in post process?
Is it by using mask layers and carefully reveal, or is there a more
efficient method?
Thanks,
--
Doron
KM D7D
C8080
http://karuzo.smugmug.com
'Good photographers never die, they just get replaced'
--

OP karuzo Contributing Member • Posts: 506
Re: Gels and wb bracketing

Thanks,
--
Doron
KM D7D
C8080
http://karuzo.smugmug.com
'Good photographers never die, they just get replaced'

Gary W. Senior Member • Posts: 2,599
Re: White balance with digital??

same question but white balance for hockey rinks...any suggestions....each rink is diff..I know that but trying to find a happy balance..thought somebody might have some ideas I could try. I am very familiar with my 20D's.
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OP karuzo Contributing Member • Posts: 506
Re: White balance with digital??

Would the ExpoDisc be an answer for you?
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Doron
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jordanw Regular Member • Posts: 421
Use a Custom WB

For each location I would suggest making a custom WB setting in your camera. You can use this in a variety of ways. I suggest the Expodisc to aid in your custom WB. It is pricey, but easy to use and dead on.

Also shoot in raw to do any final adjustments after you shoot. Some people don't worry about doing WB during shooting, but edit it in post. I do not suggest this because you shouldn't have to fix mistakes if you do it right the first time or your pretty darn close.

Chuck Gardner Forum Pro • Posts: 10,381
Capturing ambience

In almost any architectural design the lighting is an important element. The architect and lighting designer work to highlight the various feature of the building with light, sometimes to the point of having totally separate day and evening lighting schemes.

So to capture the true essence of the design you need to accurately record the ambience created by the light as it appears to the eye rather than balancing all the lights so they are the same color temperature.

For example the designer might have intentionally created a contrast between warm tungsten sources and cooler daylight from the windows to create a feeling of warmth and comfort in the interior. You'd want to WB to the exterior light to retain that look. But if you were just shooting the interior with no window in the shot for a frame of reference and contrast you'd want to WB to the tungsten sources.

Where get technically difficult is when discontinuous spectrum light sources such as florescent, and mercury / sodium vapor sources are used extensively and mixed with daylight and tungsten sources. The human eye averages out the spectrum spikes, the camera doesn't.

There are a number of different strategies which can be employed but which one is best will depend on the desired look.

Faced with a tungsten lit interior and windows you could WB to the exterior light to give the room a warm glow, balance to the WB to the exterior light and add enough fill flash to remove the warm glow except in the visible tungsten light sources. Or you could put orange gel on the outside of the windows and WB to the tungsten light (a common practice in cinema, which explains why CC gels are availabe in big rolls).

In general you'd want to WB to the most dominant or important light temp and either gel the other sources, or turn them off and simulate their illumination with other sources which match the camera WB setting or the desired color of the light appropriate to the design.

You can perform all sorts of magic in Photoshop too, but its easier if you get it as close as possible during the capture. Shooting in RAW makes it simple to shift the color balance using multiple copies of the same shot in masked layers.

CG

beware Contributing Member • Posts: 676
^^^ Custom WB -nt
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OP karuzo Contributing Member • Posts: 506
Thanks all
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Doron
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VG Veteran Member • Posts: 4,732
Re: Use a Custom WB

Jordan,

One of the main reasons people shoot RAW is the latitude of adjustment that is available with white balance. This is extremely important in constantly varying or mixed lighting setups that must be shot from different angles and light variations. An expodisc or any other fixed white balance method is going to work only if the scene lighting stays the same. Adjusting white balance in post is not correcting mistakes any more than correcting exposures is.
Regards,
VG

jordanw wrote:

For each location I would suggest making a custom WB setting in
your camera. You can use this in a variety of ways. I suggest the
Expodisc to aid in your custom WB. It is pricey, but easy to use
and dead on.

Also shoot in raw to do any final adjustments after you shoot.
Some people don't worry about doing WB during shooting, but edit it
in post. I do not suggest this because you shouldn't have to fix
mistakes if you do it right the first time or your pretty darn
close.

GTakacs Contributing Member • Posts: 766
Yes and no ;-)

Each sensor has a "native" white balance equilibrium point. What it means is that at a certain white point temperature all 3 type of receptors (R,G,B) have to be amplified by the same number so if you take a picture of a gray card under this light your red sensors will read 756 (arbitrary number just for example, bear with me) the blue will read 756 and the green will read 756.

However if you'd take a picture of this same grey card under incadescent light your red would read 756, the green would read 700 and the blue would read 463. So to compensate for this discrepancy the green and blue channels would have to be amplified. This causes noise in the blue and green channels compared to the red channel. To offset this problem you can shoot using an 80A filter and although it might not bring the three values back to 1:1:1 ratio, it would certainly be closer than before, hence making noise in the blue channel less obvious.

This same camera with the same gray card under overcast sky's would read much lower in the red channel than the blue or green so you would have to have the red channel amplified to offset the exposure causing red channel noise (prominent in blue skies when shot outdoor)

If this noise issue doesn't bother you (I personally use an 80A filter for indoor shots with incadescent lights just as you would on film cameras with daylight film used indoors) you can just take a single RAW shot and "develop" two version of it in post processing them blend them together with masks to get proper white balance.

A benefit of developing two images instead of just applying a curve to a duplicate layer of one of the white balanced pictures and blend those two is that in raw you get a bit more dynamic range before WB is applied, but not too much more.

Here is an extreme example of an indoor panorama I have shot that had a patio door with overcast shadow at sunset in the outdoor part and incadescent light in the rest of the picture.

Here is the panorama with white balance adjusted for the indoor incadescent (check out how blue the outdoor is through the patio door).

Here is the same panorama with the patio door part masked from a second image that was white balanced for the outdoor light.

Clearly this is an extreme challenge where I had to take 16 shots for the entire panorama and I took it 3 times as it's not only a WB adjusted panorama but a high dynamic range panorama that has been tonemapped as well ;-). All in all, this is one of the most complicated panorama pictures I have ever shot thanks to the high dynamic range and the different white balances.

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Barrie Davis
Barrie Davis Forum Pro • Posts: 21,460
Good photographers

karuzo wrote:

Huh? That's not how I remember it. I thought it was.......

'Good photographers never die, they just don't focus well...'
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OP karuzo Contributing Member • Posts: 506
I like it
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Doron
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