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Archive 2011 · Paul C. Buff Einstein 640 in-depth flash duration test: action v.s const...

  
 
Akoloskov
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p.1 #1 · p.1 #1 · Paul C. Buff Einstein 640 in-depth flash duration test: action v.s constant color mode


You know, I really like Paul C Buff stuff, I was using his monolights from a beginning of my studio photography. Last summer Iíve got my first pair of Einstein 640 strobes and was very pleased with the performance and most of all, with a stopping power of these digital strobes. Short flash duration was the main reason Iíve stay with PCB lighting.

On the last shot for ďMastering splashĒ article, Iíve noticed strange thing:
First, I was trying to shoot splash in a constant color mode (see spec if you are not sure what is this) and noticed that even at about 3000 t.1 (according to unit) I was getting motion blur on some of the droplets. Iíve switched to an action mode, dialed up power to get duration closer to 3000 t.1 (in action mode the same power level gives much faster flash duration) and was able to continue to shoot without any motion blur.
It was very suspicions for me, as I was throwing the water with a similar speed, and why in constant color mode, same flash duration, I was getting motion blur? Than was strange but no conclusion was made as I was not sure that the splash/droplets speed was the same in both, color and action mode.

Last weekend I was able to get back to my Einsteins and conducted more serious test. The purpose of it was to determine it there is a difference in actual (measured) flash duration in color and action mode with the same flash duration claimed (displayed on the unit). Obviously, to make this work, flash power in color and action modes would have to be very different.

Below is the setup for the test. Iíve mounted CD disk on a opened fanís shaft, and was shooting it when it was spinning and stand still, in both, constant color and action modes. Iíve decided to do a still shots so it will be easy to see the ďstartingĒ point of DOF and focus.

http://www.akelstudio.com/blog/wp-content/uploads/2011/04/pcb-einstein-flash-speed-duration-test-setup.jpg

One Einstein 640 light was used.

Because the fan I have was spinning quite fast (faster than I needed, but that was lowest possible speed) , I was dialing minimum possible flash duration in a constant color mode, whihc was 80000 t.1 at 2.5Ws. The closest flash duration in action mode was 7939 t.1 at 56 Ws.

I wanted to have the same DOF through the full test, therefore I was adjusting camera ISO settings to equalize the difference in flash output.
Camera color temp was set to 5600K, shutter 1/200 sec, F14. I had ISO=100 for action mode, ISO=1000 for constant color mode.Was shooting RAW, no adjustment was made in ACR/Photoshop, images as-is from the camera.


1. Constant Color mode:

http://www.akelstudio.com/blog/wp-content/uploads/2011/04/einstein-constant-color-mode-duration-test-spin2.jpg

Action mode:

Power output: 56Ws, flash duration: 7939t.1 , color temperature: 6249 K:

http://www.akelstudio.com/blog/wp-content/uploads/2011/04/paul-c-buff-einstein-action-mode-duration-test-spin2.jpg


Side-to-side:

http://www.akelstudio.com/blog/wp-content/uploads/2011/04/paul-c-buff-einstein-side-to-side-duration-test-spin.jpg

I see a bit more freezing action here, comparing to a constant color mode. Despite that claimed flash duration was a little slower (7939 v.s 8000 t.1). However, the difference is not that huge, probably not more than 20%, and it would be cool if Iíd have a more precise device to measure durationÖ But I do not have one. Do you see the difference in blur?

Anyway, the thing I was afraid of was not really confirmed: claimed value (number displayed on a unitís display) of duration time is relatively correct in both , action and constant color mode. Obviously, I am talking about relative values, as I did not measure absolute value of the flash duration in each mode. However, I still think that the constant color mode yields a little longer actual flash duration than claimed (Or, it might be that the action mode give shorter then claimed).

There is another interesting moment Iíve noticed though: color temperature changes in action mode. This is something what I was not aware of. Lets see:

If I look at still and spinning images done in action mode closely (talking about CD spec white text), I clearly see that color temperature does not stay the same during the flash impulse.

When disk is not spinning, this difference is not visible, but when subject is moving fast, we can easily see how color temperature gets changed: Look at the blue halo on one side of the text and brownish on another: It tells me that at the beginning of the flash impulse color temperature was even lower than claimed 6249K, 6249K at the middle, and at the end of the impulse color temperature was raised to 7000K Ė 8000K or more, looking at the intensity of blue color..

http://www.akelstudio.com/blog/wp-content/uploads/2011/04/einstein-duration-test-impulse-color-spread.jpg

The rest of the article is on the blog, as usual:

http://www.akelstudio.com/blog/paul-c-buff-einstein-640-in-depth-flash-duration-test-action-v-s-constant-color-mode/

I've got some more info there as well as my own conclusion.
Hope this will be useful for the community.
Alex




Apr 05, 2011 at 08:24 AM
E-Vener
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p.1 #2 · p.1 #2 · Paul C. Buff Einstein 640 in-depth flash duration test: action v.s constant color mode


There is another interesting moment Iíve noticed though: color temperature changes in action mode. This is something what I was not aware of. Lets see:

If you had either looked at the manual or the back panel of the Einstein you would have been aware of that.



Apr 05, 2011 at 09:40 AM
Akoloskov
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p.1 #3 · p.1 #3 · Paul C. Buff Einstein 640 in-depth flash duration test: action v.s constant color mode


E-Vener wrote:
If you had either looked at the manual or the back panel of the Einstein you would have been aware of that.


Sorry, but you've missed the point: i was not surprised that in action mode color was changing based on the output power, but it WAS NOT CONSTANT DURING THE IMPULSE. 2000K-3000K difference seems to be a lot...

That means that it was not 6400K as stated on the back panel of the unit.
Please read the article and look at the examples more carefully:-)

This is what we have in manual:
In ACTION MODE, Einstein allows the color temperature to rise slightly as power is reduced as a means of achieving the fastest possible flash durations. Both the t.1 flash duration and the color temperature are displayed on the rear panel LCD in all modes and at all power settings.



Apr 05, 2011 at 11:31 AM
billatwkrp
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p.1 #4 · p.1 #4 · Paul C. Buff Einstein 640 in-depth flash duration test: action v.s constant color mode


Well, think about how a flash pulse is created, there are graphs on the Buff web site. The pulse starts out, goes to a peak, then rapidly drops off. Right? Well, it seems to me that the color temperature would be changing as the intensity changed. Lower temp at lower powers, high temp at the peak and lower at the tail.

The color temperature reported by the flash would be the average over the entire pulse.

Now it would seem to me that the way to keep a constant color over the entire power range would be to modify the tail of the flash pulse to even the average color temperature out. (I'm assuming the build-up and peak are determined by the power settings on the flash and are more or less fixed.)

That would explain the longer flash duration in color mode, it has a longer warmer tail (under the t.1 power level) to offset the blueness of the peak.


I'm really just pulling this theory out of my butt, I have no idea if it's right or not. But it makes sense to me.



Apr 05, 2011 at 11:45 AM
E-Vener
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p.1 #5 · p.1 #5 · Paul C. Buff Einstein 640 in-depth flash duration test: action v.s constant color mode


Sorry, but you've missed the point: i was not surprised that in action mode color was changing based on the output power, but it WAS NOT CONSTANT DURING THE IMPULSE. 2000K-3000K difference seems to be a lot...

Actually this is true of virtually all electronic flash. At the beginning of the pulse, which is higher energy , the light is bluer (as with hotter flames being bluer in color than lower temperature flames) than later in the pulse. And the color temp is an average reading of the full pulse above the t0.1 energy threshold. The only flash I am aware of this is not true for is the Broncolor Scoro pack.



Apr 05, 2011 at 11:45 AM
E-Vener
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p.1 #6 · p.1 #6 · Paul C. Buff Einstein 640 in-depth flash duration test: action v.s constant color mode


You could also be seeing sensor and bayer filter array and interpolation fringing.


Apr 05, 2011 at 11:50 AM
Akoloskov
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p.1 #7 · p.1 #7 · Paul C. Buff Einstein 640 in-depth flash duration test: action v.s constant color mode


E-Vener wrote:
Actually this is true of virtually all electronic flash. At the beginning of the pulse, which is higher energy , the light is bluer (as with hotter flames being bluer in color than lower temperature flames) than later in the pulse. And the color temp is an average reading of the full pulse above the t0.1 energy threshold. The only flash I am aware of this is not true for is the Broncolor Scoro pack.


Yes, this is how I've explained it to myself too.
BTW, in color mode it has very the same K across the impulse.



Apr 05, 2011 at 12:10 PM
Akoloskov
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p.1 #8 · p.1 #8 · Paul C. Buff Einstein 640 in-depth flash duration test: action v.s constant color mode


E-Vener wrote:
You could also be seeing sensor and bayer filter array and interpolation fringing.


May be, but why no such thing seen in a still shot of the same setup/subject? Only when disk is spinning and only in action mode i see bluish edge..



Apr 05, 2011 at 12:11 PM
kenyee
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p.1 #9 · p.1 #9 · Paul C. Buff Einstein 640 in-depth flash duration test: action v.s constant color mode


Probably just the normal pulse wave for the different color edges and you'd probably see it w/ others as well (except maybe the high end Bronco Verso color-accurate packs)...have any other strobes to test with? Might also be interesting to try that w/ a speedlight...


Apr 05, 2011 at 01:53 PM
Paul Buff
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p.1 #10 · p.1 #10 · Paul C. Buff Einstein 640 in-depth flash duration test: action v.s constant color mode


This should explain it all

http://blog.bronimaging.com/2010/01/broncolor-scoro-enhanced-color-temperature-control-ectc/

No flash produces constant color across the duration of the flash. I (and Rob Galgbraith) have done a zillion tests like this. When you talk about "stopping action", the velocity of the moving object defines everything. You won't stop a bullet with 1/10,000 second, but you can stop a baseball.

As for the difference in the blue/red fringing, again, look at the link. Also, if you equalize the color balance of the action and color mode shots I believe you will see approximately the same color shift during flash duration, and s very similar motion freezing effect . . . as you will on a Grafit (but with more overall blur) or on an Elinchrom or anything else, but with infinitely more blur.

Speedlights exhibit less color shift through the duration because the tube is linear and operating at wayyyyy less current density.

On a very rapidly spinning wheel such as show here you will see some difference between action and color modes because the tube is operating at different anode voltages, current densities and tail shapes.

I strongly suggest renting a Verso or Grafit pack and head and repeat these shots . . . I plan to do this myself. I believe you will find the same characteristics, but with a minimum t.1 duration of 1/8000 instead of 1/13,500 . . . more blur.



Apr 05, 2011 at 04:13 PM
E-Vener
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p.1 #11 · p.1 #11 · Paul C. Buff Einstein 640 in-depth flash duration test: action v.s constant color mode


Akoloskov wrote:
May be, but why no such thing seen in a still shot of the same setup/subject? Only when disk is spinning and only in action mode i see bluish edge..


I am basing my hypothesis on the combination of the nature of Bayer filter and color interpolation to create a full set of color values for each photosite in the sensor based in that site and the surrounding nine photosites and a rapidly moving object. Notice that you are seeing it where a clearly defined edge of a white object is surrounded by much darker areas.



Apr 05, 2011 at 06:15 PM
honorerdieu
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p.1 #12 · p.1 #12 · Paul C. Buff Einstein 640 in-depth flash duration test: action v.s constant color mode


Disclaimer: I'm not the most technical person when it comes to flash and strobes.

But RE: color shifting -- does it really matter? For 499 bucks, I think the PCB Einstein is quite a steal when compared to the branded hotshoe flashes that are going for 445 to 490 dollars, the last time I checked. Profotos and Elinchrom are going for at least 1000 bucks per unit.



Apr 05, 2011 at 06:20 PM
Akoloskov
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p.1 #13 · p.1 #13 · Paul C. Buff Einstein 640 in-depth flash duration test: action v.s constant color mode


@Paul Buff,
Thank for confirming. This is what I sort figure out myself, the temperature change across the impulse.
BTW, why we do not see that much of difference in color in constant color mode? Does Einstein has impulse cutoff in color mode?

I'll do the same test with speedlites and Broncolor pack as soon as I'll get it from my vendor.

@E-Vener, have no idea of what you are talking about:-) But I guess it should be the same situation with moving object in constant color more as well?

@honorerdieu Did I say Eisnteins are bad? I love them, but I need to know my gear as deep as I can, so I'll get most from it.





Apr 05, 2011 at 07:05 PM
Paul Buff
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p.1 #14 · p.1 #14 · Paul C. Buff Einstein 640 in-depth flash duration test: action v.s constant color mode


honorerdieu wrote:
Disclaimer: I'm not the most technical person when it comes to flash and strobes.

But RE: color shifting -- does it really matter? For 499 bucks, I think the PCB Einstein is quite a steal when compared to the branded hotshoe flashes that are going for 445 to 490 dollars, the last time I checked. Profotos and Elinchrom are going for at least 1000 bucks per unit.


But price isn't really the issue. Neither Profoto not Elinchrom make IGBT controlled flash unit, and cannot achieve action stopping anywhere even close to the Einstein, and both exhibit the same color shift at the beginning and end of the duration. Only Broncolor (and Photogenic Solaire) make IGBT models and they only go down t0 1/3500 second t.1

Notice on the first Broncolor link the shift is clearly shown and it's explained the "Average comes out 5500įK" This is what you will see when you look at pictures in RAW. The same applies to non IGBT lights such as AB, Profoto, Elinchrom, etc., except the reddish trailing edge is waaaaay longer. The short leading edge is typically about the same length . . . about 40usec (1/25,000 second).

The second link below describes Profoto's attempt at more constant color, without using IGBT technology, and the disastrous results as pointed out by Broncolor (and reported by Rob Galbraith).

http://blog.bronimaging.com/2010/01/broncolor-scoro-enhanced-color-temperature-control-ectc/


http://blog.bronimaging.com/2010/04/profoto-not-working-cancel-the-shoot-no-call-broncolor-instead/

Do the same test with Elinchrom and Profoto high end monolights and you'll be shocked at how poorly either can stop action compared to Einstein or Broncolor.. Plus you'll find as much as 700įK of color shift from full power to minimum power. AB1600 and Elinchrom are essentially identical in color shift VS power level and in t.1 flash duration (about 1/600 at Full and 1/300 at minimum, and about 350įK color shift from full to minimum. D1 has slightly shorter t.1 duration but even more color shift VS power.



Apr 05, 2011 at 08:22 PM
Paul Buff
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p.1 #15 · p.1 #15 · Paul C. Buff Einstein 640 in-depth flash duration test: action v.s constant color mode


Akoloskov wrote:
@Paul Buff,
Thank for confirming. This is what I sort figure out myself, the temperature change across the impulse.
BTW, why we do not see that much of difference in color in constant color mode? Does Einstein has impulse cutoff in color mode?

I'll do the same test with speedlites and Broncolor pack as soon as I'll get it from my vendor.

@E-Vener, have no idea of what you are talking about:-) But I guess it should be the same situation with moving object in constant color more as well?

@honorerdieu Did I say Eisnteins are bad? I love them, but I need to
...Show more

I believe you'll see a similar result with Broncolor IGBT packs, but less of this effect with speed lights . . . because the much smaller flashtube ionizes and shuts off much more quickly.

As for the difference between color and action modes, as I said, if you equalize the color balance I think they will look very similar. There will still be a slight difference between modes because the ionization and discharge curves are somewhat different.

As for Ellis, I believe he is referring to lens aberrations. Both Rob Galbraith and myself have ruled this out . . . the cause is explained by Broncolor and our German tube manufacturer has conveyed to us that different tube designs, Xenon fill pressure and geometry vary in this phenomenon, with low power low high impedance low power tubes typically used in speedlights minimizing the effect over high power low impedance circular tubes found in studio flash units. (It takes longer to ionize and shut off a high power tube.)

Good discussion, but I don't think you will see the effect of this in the gamut of action stopping pictures such as sports, dance, etc. in Einstein or Broncolor.



Apr 05, 2011 at 08:37 PM
BrianO
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p.1 #16 · p.1 #16 · Paul C. Buff Einstein 640 in-depth flash duration test: action v.s constant color mode


Paul Buff wrote:
...As for Ellis, I believe he is referring to lens aberrations.


I didn't know lenses had Bayer arrays, nor that lenses did color interpolation based on adjacent pixels.



Apr 06, 2011 at 01:23 AM
Akoloskov
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p.1 #17 · p.1 #17 · Paul C. Buff Einstein 640 in-depth flash duration test: action v.s constant color mode


@Paul Buff
Now I really want to test Profoto and Broncolor the same way:-)
BTW, have added 580EX-II shots made within the same test procedure from 1/8 through 1/128 of power. Quite interesting results: http://www.akelstudio.com/blog/paul-c-buff-einstein-640-in-depth-flash-duration-test-action-v-s-constant-color-mode/#speedlite :-)

As you said , there was no color separation from the linear tube impulse. But the stopping power.. Einsteins looks really impressive in such comparison.

Thank you.

Edited on Apr 06, 2011 at 08:16 AM · View previous versions



Apr 06, 2011 at 06:56 AM
E-Vener
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p.1 #18 · p.1 #18 · Paul C. Buff Einstein 640 in-depth flash duration test: action v.s constant color mode


If the OP is using Adobe Camera Raw or Lightroom 3.x to process his raw files he should at least try the fringing correction tools to see if they address the red fringe and blue fringing in these photos. That he isn't seeing the issue with his Einstein in constant color mode sort of rules that out but it is worth a shot.

As to why he isn't seeing it in Constant color mode speaks to how Paul understands the issues and found a way to solve it through programming energy release.

These days I very rarely use my Einstein's in Action mode just as I very rarely use ISO settings above 6400 on my EOS 1D Mk IV or D3s cameras. But just because I don't regularly use those options doesn't mean I am not glad to have them when I do need them.



Apr 06, 2011 at 07:25 AM
kenyee
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p.1 #19 · p.1 #19 · Paul C. Buff Einstein 640 in-depth flash duration test: action v.s constant color mode


BrianO wrote:
I didn't know lenses had Bayer arrays, nor that lenses did color interpolation based on adjacent pixels.


I think he means stuff like longitudinal chroma aberration which causes different light colors to land at different points on the sensor, so you can't correct for it very well in post:
http://en.wikipedia.org/wiki/Chromatic_aberration
The Tamron 70-300 (not their new VC) I have is fairly well known for this...it shows up as purple fringing at high contrast white/black edges. Doesn't look like it to me though.

@Alex: that is fairly impressive...I had thought that speedlights at min power would still be faster. Hummingbird shooters gang up multiple speedlights at min power just to freeze wings in flight. Looks like they should be using Einsteins instead so they can cut down on the #speedlights and get more depth of field from the power level



Apr 06, 2011 at 08:16 AM
Akoloskov
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p.1 #20 · p.1 #20 · Paul C. Buff Einstein 640 in-depth flash duration test: action v.s constant color mode



BrianO wrote:
I didn't know lenses had Bayer arrays, nor that lenses did color interpolation based on adjacent pixels.

I think he means stuff like longitudinal chroma aberration which causes different light colors to land at different points on the sensor, so you can't correct for it very well in post:
http://en.wikipedia.org/wiki/Chromatic_aberration



I might be really stupid, as I can't understand WHY the same lens, same aperture and same shutter speed on the SAME subject in one case has aberration and in another does not.


My understanding is that this is a color difference during the impulse, not aberration: look at speedlite test, there is no aberration...

I really want to see how profoto and broncolor will manage this test..

Hummingbird shooters: its hard to beat little battery powered strobes because of it's size:-) Glad I am a studio photographer:-)



Apr 06, 2011 at 09:26 AM
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