What color is ambient lighting?

Let's say you're using your strobe to overpower the ambient lighting. Since shutter speed controls ambient and is likely to be a longer duration than the flash exposure, does that mean that whatever tones are in ambient light will make it into the photo?

For example, let's say that a wedding is lit up with purple lights and there's a lot of it in ambient. The flash exposure will light up the subject (wedding couple) and you can achieve perfect exposure and skin tones without the purple, but the purple will still be in the background if you've set your shutter appropriately?

Examples?

Overpower it with your shutter speed and you can kill the ambient

Nathan wrote in post #18383586
Let's say you're using your strobe to overpower the ambient lighting. Since shutter speed controls ambient and is likely to be a longer duration than the flash exposure, does that mean that whatever tones are in ambient light will make it into the photo?

If your exposure allows for ambient to contribute to the exposure, you will have mixed temperatures. If your exposure is mostly, or entirely flash/strobe produced, it will be the temperature of your flash/strobe. This is why we use gels sometimes to match the flash/strobe to ambient temperature, so they blend (when ambient produces enough exposure to show up). CTO gels for example with tungesten lights. If your camera settings stop out all ambient light (or most of it), then temperature will be that of the flash/strobe. Conversely, allow ambient to show up (say with higher ISO, or dragging the shutter, it will include ambient temperature, and your flash will likely be a different temperature). Flashes in general are inehrently approximately daylight temp (around 5200K +/- 200 or 400K or so). So you can guess that if the ambient temp is something like tungsten, you'll want a gel to match it.

Very best,

Note that when you bounce the light from the strobe, you get a 'unified' colour.

https://books.google.c​a …he%20colors%20m​ix&f=false

The extent to which the ambient light 'contaminates' the color temp of the light which you add via flash, is wholly dependent upon the proportion, and the degree to which the 'other light' differs from the flash...ambient at 3000K vs. flash at 5500K is different from colored gelled (e.g. purple) light vs. flash at 5500K.


I have not done extensive testing to quantify even warm ambient vs. flash but it is not difficult to simply do an experiment for yourself...after all digital exposures are 'free'!

Without having done a specific experiment to quantify, I would have suspected that if flash were +2.5EV more powerful than colored ambient, that would largely eliminate color light contamination. Having just done a test, Now I know I was wrong about a color light contamination!

In this test I shot only by modelling light with both sources at the same intensity and distance. But both heads had grids to limit the light spread angle; the right source started -2.1EV dimmer than the ungelled Left source (although at the same distance). Then I put a deep magenta Rosco 44 gel over the Right source.

.

1. Shot 1 has Left > Right by 2.3EV
   
2. Shot 2 has Left > Right by 2.7EV (Right source was moved farther back from subject to achieve this)
   
3. Shot 3 is entirely illuminated by Left source
   

All shots set to same WB setting, and the shadow zone in shot 3 was used as the basis for eyedropper WB sample point.

Nathan wrote in post #18383586
For example, let's say that a wedding is lit up with purple lights and there's a lot of it in ambient. The flash exposure will light up the subject (wedding couple) and you can achieve perfect exposure and skin tones without the purple, but the purple will still be in the background if you've set your shutter appropriately?

Examples?

Remember that ambient (continuous) light is controlled by shutter and aperture. If you employ HSS or keep shutter speed at X-sync, then you're free to combine ambient and flash but ugly mixed color temperatures may result. Gels can help if ambient is one color temperature, with halogen-fluorescent mixes being a common exception. You can usually drive indoor ambient to zero with suitable exposure settings, then light the subject with your flash. To retain b/g ambient for mood while avoiding an ugly mix, keep your subject "in the shade":

So it is general consensus not to mix color temperatures, then? For example, if the wedding was themed with purple lights, would you want to kill all of ambient lighting for the sake of the photo? Or is there a balance point somewhere that you expose and light your subject to get the best skin tones, but let some of that ambient into the background?

I like to mix and use the ambient light. Find out wat color temperature the ambient light is and gel you flash. Set the camera to that Kelvin value or just Tungsten.

Tungsten is an orange like filter CTO and if you set the camera also to it.

A trick to find the right value is to set the camera in liveview and then change the color temperature on the camera. One eye on the screen and one at the area in front and compare.

Nathan wrote in post #18384015
So it is general consensus not to mix color temperatures, then? For example, if the wedding was themed with purple lights, would you want to kill all of ambient lighting for the sake of the photo? Or is there a balance point somewhere that you expose and light your subject to get the best skin tones, but let some of that ambient into the background?

It sounds like from your questions, you are possibly shooting your first wedding or maybe just have a very specific interest in what wedding photogs do?

A wedding day usually has many aspects to it and results in many different types of pictures in many different locations - including, but not always, a very dark purple lit reception as an example that the couple either deliberately chose or that is just what was available locally. Either way, or at least hopefully, the photographer captured formal bride, groom and family formal portraits in a more controlled and pre-planned lighting environment earlier in the day. The crazy mixed lighting, common at receptions, should really just be embraced and captured to record the environment that was; or, you can bring in $50k of very powerful strobes and nuke the place.

Weddings tend to be the easiest situations to draw examples from. I've been taking photos of events for years (volunteer) and never truly spent any time understanding wb, color temperature and flash. I'm one of those photographers who picked up a camera and was too afraid to learn flash. I want to get better now.

Wilt wrote in post #18383730
The extent to which the ambient light 'contaminates' the color temp of the light which you add via flash, is wholly dependent upon the proportion, and the degree to which the 'other light' differs from the flash...ambient at 3000K vs. flash at 5500K is different from colored gelled (e.g. purple) light vs. flash at 5500K.


I have not done extensive testing to quantify even warm ambient vs. flash but it is not difficult to simply do an experiment for yourself...after all digital exposures are 'free'!

Without having done a specific experiment to quantify, I would have suspected that if flash were +2.5EV more powerful than colored ambient, that would largely eliminate color light contamination. Having just done a test, Now I know I was wrong about a color light contamination!

In this test I shot only by modelling light with both sources at the same intensity and distance. But both heads had grids to limit the light spread angle; the right source started -2.1EV dimmer than the ungelled Left source (although at the same distance). Then I put a deep magenta Rosco 44 gel over the Right source.

.

1. Shot 1 has Left > Right by 2.3EV
   
2. Shot 2 has Left > Right by 2.7EV (Right source was moved farther back from subject to achieve this)
   
3. Shot 3 is entirely illuminated by Left source
   

All shots set to same WB setting, and the shadow zone in shot 3 was used as the basis for eyedropper WB sample point.

Boom!

I just read up on using CTO on the flash and lowering the Kelvin temp of the camera. Blown away. Why would I ever want to shoot without a gel again?

Heya,

I prefer to use ambient when possible, usually becasue there's a mood or something from it you want to retain (like color). Unless you have multiple lights to spread around and create ambient light with (like some do), incoporating ambient will give it a more natural look. If you stomp out ambient and flash the subject, it looks flashed. If you have ambient, and you blend flash with a gel to have similar temps (it doesn't have to be equal, simply similar), it will look more natural, less like flash, and you can even use direct flash this way as fill with similar temps and get a natural look.

This also applies to outdoor ambient. Flash is approximately 5200K +/- a few hundred, which is close to day light temperature. Early morning is more blue. Late evening is more gold/orange. So using gels to match your flash temperature to outdoor ambient also applies here, so that your warm sunny golden hour photo doesn't have a warm ambient and a cold blue flashed subject. I use 1/4th CTO commonly for this to warm it up and blend ambient to flash in that situation. You can also use gels to do creative things, like create blue skies with a natural temp subject, etc. Gels also allow you to color a background to take advantage of a sterile looking enironment and add pop.

Very best,

I think you obsess on the issue of having everything to be consistent in color temperature. The mind is forgiving. If it sees someone primarily illuminated by window light, the fact that that window light is a bit cool in a photo is a no-brainer...our brains are accustomed to seeing cool window light and at the same time seeing warm incandescent sources in the room some distance away. Here are two examples of that mix, shot at different wedding receptions

Cause, sometimes you want ambient, sometimes you don't, and sometimes it just takes a master.

gregory heisler