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Archive 2015 · Is it normal for color to change on strobes in lower power?

  
 
keano12
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p.1 #1 · p.1 #1 · Is it normal for color to change on strobes in lower power?


Hi guys,

Is this normal regarding color consistency to change when lowering the power on strobes?

First images was shot at TTL/HSS 1/4000 f2.2 and has warm normal tones.

Second was shot at TTL 1/160, F2.8 and is much cooler.

I took a the same pic with my angry girl friend made her get out of bed and got the same results. So if I shoot at low power is it normal for cover temperatures?

TTL - HSS - 1/4000 - f2.2

TTL - 1/160 - f2.8



May 21, 2015 at 05:16 PM
Gregg Heckler
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p.1 #2 · p.1 #2 · Is it normal for color to change on strobes in lower power?


Are you talking about a Speedlight or a studio type strobe? There is lot going on here. You have the white doors and reflection in the picture frame causing the under exposure in the second image but I'm not sure how the first image was over exposed at 1/4000 of a second. My guess is TTL/HSS saw the reflection in the picture as a bright BG and caused the high shutter speed.

But, yes color temperature can and will change as power changes. The amount depends on the performance and quality of the strobe. You typically won't see it with a Speedlight particularly if you are in auto white balance.



May 21, 2015 at 05:46 PM
keano12
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p.1 #3 · p.1 #3 · Is it normal for color to change on strobes in lower power?


Hi I purposely shot in HSS to push the flash in TTL. Not concerned so much on exposure as the color change colder on the Indra at lower power.


May 21, 2015 at 06:04 PM
WayneF
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p.1 #4 · p.1 #4 · Is it normal for color to change on strobes in lower power?


Yes, it is normal to see a little color shift with flash power level. Most monolight studio lights get slower and more red at low power (a small few work more like speedlights). Speedlights are the opposite, they get faster and more blue at low level. Not extreme, some ignore it, either don't know or don't care, and there are other factors affecting color too, but it's easy to fix white balance.

It's just the way the flash works. A flash is a very rapid and strong pulse of power, which then slowly (2 or 3 milliseconds) trails off to nothing. A speedlight implements lower power by suddenly chopping off the light output, which truncates its trailing tail. So Full power is reddish (includes cooler tail), but chopping off the trailing cooler tail (red is cool) leaves it more blue. We might as well plan on it, because that's the way it works.

We can use a white balance card ($5 Porta Brace white balance card at B&H is a good one). Even something intended to look neutral white (like an envelope or T-shirt or church steeple) can be used, not always perfect, but often pretty good, and normally better than nothing (if we pick something actually white). We can include this card in the scene (in the same light), maybe at the edge of the frame where we can crop it off. Or more commonly, just in the first "test" picture in the situation. Then better photo software has a White Balance Tool where we just click the (neutral) card in the picture, and presto, perfect color, no color cast.

For one example, see http://www.scantips.com/lights/whitebalance.html and specifically, nearly 2/3 down the page, to the several pictures of the yellow cup, where it says "Flash color temperature varies with flash power level". The second column shows Full and 1/64 power at standard Flash WB, and one is pink and one is blue. The whole page is about correcting it.

If you have a few minutes, a more detailed view is the video on the page http://www.scantips.com/lights/shootraw.html
That is about Raw, but the WB idea is the same (raw editors process JPG too, and have real good tools).



May 21, 2015 at 06:10 PM
keano12
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p.1 #5 · p.1 #5 · Is it normal for color to change on strobes in lower power?


Great info. I read another something from Neil van Niekerk about the B1's also having color shifts at lower power that it is normal you show. He told me go shot in normal sync at all the power settings. You links are great. still going through the first one. I have the x-rite passport checker. I'll try that out with it.


May 21, 2015 at 07:31 PM
Gregg Heckler
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p.1 #6 · p.1 #6 · Is it normal for color to change on strobes in lower power?


Sp it's an Indra then? Their specs say 5500K +/- 200K. No way that's only a 200K color shift over 4 stop stops. You should do to the same test without the HSS on over the entire power range.


May 21, 2015 at 07:36 PM
keano12
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p.1 #7 · p.1 #7 · Is it normal for color to change on strobes in lower power?


Hi Gregg - Yup that's what I am going to do.


May 21, 2015 at 08:02 PM





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