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Mixed Light Sources: Using Daylight Flash with Tungsten Lit Stage!

Asher Kelman

Asher Kelman

OPF Owner/Editor-in-Chief
Passport_AdobeRAW_lg.jpg


Xrite color Checker tool found here.
​

I have now been able to overcome the harsh vertical stage light by using flash from the balcony. Overhead light alone can be harsh. The light from above may leave unlit eye sockets and project shadows of glasses on the cheeks. In addition foreheads and dainty hands get blown out! Using stage light alone, one overcome these problems very easily!

However, the overhead light does have some occasional charm with coloring and presence of Flemish paintings, especially with young Asians musicians

One loses that with dominant flash. However, there's a new risk of unsightly shadows from violin bows on the faces of players! That was a bad surprise. So now I'm considering dropping the power of the electronic flash so that it can just fill in the shadows caused by the overhead lights In turn, the stage lights from above can decrease shadows from the electronic flash. So let's say we now do that and 50% of the light is now coming from the front. So let's say we can do that and now we have 5500 degree light from the flash and ~ 3400 degree light from the lights above the stage.

I'm wondering whether or not it would be helpful to gel the flash so as to match the color temp of the stage lights?

Another approach is to measure the combine stage and flash color temp and use a filter on the camera lens to correct it or else simply set the camera for that color temp.

So, what suggestions are there for getting the best color with the two light sources. I have zero control over stage light intensity but good control over the flash intensity. I could have different gels available, but I could likely only bring the flash temp to a general range of the stage light.

Is it worthwhile?

Of course I can still have a gray card and even a color checker card by Gretag Macbeth or Xrite, but that's after the fact. I am thinking that having just ~ one color temp for stage and flash should give a better picture. Is that just intuition of is there science to back that assertion? IOW, do you think it makes a difference in practice?

So the choice is

  1. Use the lights as they are and correct afterwards

  2. Use the lights as they are, measure the combined temp and set that into the camera

  3. Gel the flash to match the stage lights and set the camera to that temperature

  4. Measure the color temp of the combined light, balanced or not and add a filter to the lens to correct
    that.

  5. Do any of the above but use an Xrite color checker and be done with it!

Asher
 
Doug Kerr

Doug Kerr

Well-known member
Hi, Asher,

The challenge you face here may not be the most difficult of color balancing acts, but it has a lot of tough ingredients, and so is an important "test case" in this area. I think that your conclusions here can be the basis of an important body of practice. I applaud you bringing this case to our attention.

I have almost no personal experience in this area, but let me make some observations from a "theoretical" basis.

My guess is that integrating any substantial amount of flash illumination into this scenario will best be served by gelling the flash to nearly match (in chromaticity) the prevailing illumination on the performers. I don't know right now how best to do that.

Hopefully we could judge the chromaticity of the prevailing stage illumination from measurements or test shots made during "light setup" or whatever. I'm sure that there are practical ways to determine from that, and knowledge of the chromaticity of the (bare) flash output, to determine what gel would be the best. There may be reference material of interest to the cinematography world (rumored to have some presence near you) that would be helpful here.

I don't think that an "exact" match - even if that would be a meaningful notion, given the variations in stage lighting across the scene - would be necessary. A serious approximation might make an enormous improvement in your result.

Using overall white balance color correction based on the net chromaticity of the stage lighting plus the flash on particular subjects is not likely to do the job. You mention a prominent reason - "off-color" shadows from string bows and the like.

Best regards,

Doug
 
Asher Kelman

Asher Kelman

OPF Owner/Editor-in-Chief
Doug Kerr said:
Hi, Asher,

The challenge you face here may not be the most difficult of color balancing acts, but it has a lot of tough ingredients, and so is an important "test case" in this area. I think that your conclusions here can be the basis of an important body of practice. I applaud you bringing this case to our attention.
Click to expand...

I have no shame! :)

Doug Kerr said:
Hopefully we could judge the chromaticity of the prevailing stage illumination from measurements or test shots made during "light setup" or whatever. I'm sure that there are practical ways to determine from that, and knowledge of the chromaticity of the (bare) flash output, to determine what gel would be the best. There may be reference material of interest to the cinematography world (rumored to have some presence near you) that would be helpful here.
Click to expand...

I have been thinking of buying a used Color Meter. That would allow me to check the color temperature of the stage light and flash separately. However, for Chromaticity, we need not only the dominant light, but the distribution either side of that wavelength. So the color meter will give me a lead in choosing the right gel for the lights. Then the color checker card placed across the stage at intervals would allow correction of the entire image broken up, if need be, into zones for final correction.

Doug Kerr said:
I don't think that an "exact" match - even if that would be a meaningful notion, given the variations in stage lighting across the scene - would be necessary. A serious approximation might make an enormous improvement in your result.
Click to expand...

This is my instinct, but I would like a scientific backing. Perhaps a seriously detailed profile of the light incident light flux versus wavelength would be needed to really make some provable argument.

Thanks,

Asher
 
M

Mark Hampton

New member
Asher Kelman said:
Passport_AdobeRAW_lg.jpg


Xrite color Checker tool found here.
​

Asher,

if this gizmo does that to the models face I would stay well clear... Just work in B&W (toned of course) and theres no real issue with colour !!

Problems with colour photography.

1 - Its a cheap alterinative to B&W

2 - Its supposed to be more "real" but is less - re all dougs and barts posts on spaces etc..

3 - Humans have only been seeing in colour since the middle ages - just because somethings new doesnt mean its best or of any real value.

4 - Colour is just tone.

on a seroius note take a grey card under expose by 2.33ev and guess.
Click to expand...
 
Asher Kelman

Asher Kelman

OPF Owner/Editor-in-Chief
Mark Hampton said:
Asher Kelman said:
Passport_AdobeRAW_lg.jpg


Xrite color Checker tool found here.
​

Asher,

if this gizmo does that to the models face I would stay well clear... Just work in B&W (toned of course) and theres no real issue with colour !!
Click to expand...

That's so funny! You'd think they got that right. The PR department likely took an image in Adobe RGB and posted it in sRGB or something like that. So often camera companies give out sample photographs for new cameras that are less than optimum too!

Mark Hampton said:
Problems with colour photography.

1 - Its a cheap alterinative to B&W

2 - Its supposed to be more "real" but is less - re all dougs and barts posts on spaces etc..
Click to expand...

The truth for me has been in my youth that B&W was real photography and color was an experiment and the toughest assignment.

Now all that seems forgotten. Cameras are digital an autosensing and give pretty darn pleasing output in most circumstances.

Too many folk think of B&W as a merely a rescue procedure for failed color. Now for me, B&W is the hardest challenge as the standards that we expect are so high and iconic references for any scene are so majestic and refined. I have a new series to shoot and a request for a stunning B&W scene. I must admit, that is a humbling thought. Color, I must admit, however ambitious is far easier to accomplish to a good or even great standard.

Mark Hampton said:
4 - Colour is just tone.
Click to expand...

but for each wavelength, LOL :) and no change in tone is needed to have an entire picture. For B&W, one tone cannot hold much detail!

Asher
Click to expand...
 
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