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FORUMS General Gear Talk Flash and Studio Lighting 
Thread started 27 Nov 2017 (Monday) 21:23
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Results of Flash Duration Measurements on My Various Strobes

 
williaty
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Dec 07, 2017 17:18 |  #31

Jotto123 wrote in post #18511050 (external link)
Sorry. My interest is currently in research phases. I just started looking for strobes adequate enough to freeze dance movements and jumps in a studio setting (and hopefully won't break the bank as I'm just an amateur at this point).

I've shot a lot of dancers this year. My results are that t.1 durations in the range of 1/1500 to 1/2000 will reliably freeze dancers in mid air (including hair). If they're REALLY flinging their arms or legs around, 1/2000 will result in sharp bodies but just a hint of blur at the finger tips/toes. T.1 durations longer than 1/1000 consistently produced blur no matter what.




  
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Robertk2012
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Dec 08, 2017 03:44 |  #32

williaty wrote in post #18512905 (external link)
I've shot a lot of dancers this year. My results are that t.1 durations in the range of 1/1500 to 1/2000 will reliably freeze dancers in mid air (including hair). If they're REALLY flinging their arms or legs around, 1/2000 will result in sharp bodies but just a hint of blur at the finger tips/toes. T.1 durations longer than 1/1000 consistently produced blur no matter what.

I can confirm those numbers are correct!




  
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williaty
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Dec 18, 2017 00:06 |  #33

I recently acquired a Flashpoint eVolv 200 and tonight I ran the testing on it. I was very surprised at how slow it was (note that I'd never bothered to look up what the manufacturer claimed it could do, so I have no idea how these compare to claimed specs). It's slower than a Xplor 600 down to about 10J (about 1/16 -1/3rd power, what a stupid way to write that, btw). It's slower than the Einstein in Action mode all the way down to 1/64 -1/3 and even slower than the Einstein in Color mode down to 1/4 -1/3. The thing that impressed me in a positive way, though, was the repeatability of the duration! down to 1/16th power, the pops were identical to better than the measuring resolution of the meter. Below 1/16th power, there was some measurable variation, but it was way less than 5%.

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Robertk2012
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Dec 18, 2017 08:16 as a reply to  @ williaty's post |  #34

What power level are you getting 1/2100? Thanks!




  
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williaty
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Dec 18, 2017 17:26 |  #35

Robertk2012 wrote in post #18520746 (external link)
What power level are you getting 1/2100? Thanks!

I assume you mean with the eVolv 200 since that's what I just added. It hits 1/2100 at -2f or 1/4 or 50J, however you feel like writing it.




  
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jlafferty
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Dec 18, 2017 22:28 |  #36

I shoot dancers a lot. Hair, finger tips, edges of wardrobe... tack harp is 1/5000 minimally.

williaty wrote in post #18512905 (external link)
I've shot a lot of dancers this year. My results are that t.1 durations in the range of 1/1500 to 1/2000 will reliably freeze dancers in mid air (including hair). If they're REALLY flinging their arms or legs around, 1/2000 will result in sharp bodies but just a hint of blur at the finger tips/toes. T.1 durations longer than 1/1000 consistently produced blur no matter what.


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Dec 18, 2017 22:33 |  #37

Let us not forget that a bit of blur conveys the SENSE OF MOTION, we need not have everything totally frozen in Carbonite!


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jlafferty
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Post edited 5 months ago by jlafferty. (2 edits in all)
     
Dec 18, 2017 22:33 as a reply to  @ williaty's post |  #38

Two questions...

Your Xplor600 plots out at around 512ws, yes? This is great info. I metered the Streaklight 360 (non-TTL) and it was the same or within a tenth of the 310-320ws Alien Bee. So I call it a 300ws light. I assumed the Xplor naming played similar games and had been casually calling it a 500ws light. I like underpromising.

Second question, and apologies if you mentioned this already: what're you measuring with? I've been testing a Lumu and it shows similar graphs and I wonder how accurate it is and what I'd use to independently verify it.

edit: I see. You've got the Lumu, too. Can you provide a link to the Illuminati meter you've purchased? Our needs overlap, and I can only find it as a pre-order Kickstarter kind of thing.


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williaty
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Dec 19, 2017 17:44 |  #39

jlafferty wrote in post #18521402 (external link)
Two questions...

Your Xplor600 plots out at around 512ws, yes? This is great info. I metered the Streaklight 360 (non-TTL) and it was the same or within a tenth of the 310-320ws Alien Bee. So I call it a 300ws light. I assumed the Xplor naming played similar games and had been casually calling it a 500ws light. I like underpromising.

No electrical input power measurements were made (as there's no way to do so). The full power data point for the Xplor is plotted at 600J because that's what the manufacturer claims it is. If you don't trust them, take it apart and count the caps. Your comparison with the B800 is also somewhat meaningless.

What everyone forgets is that the Watt-second (we really should call it Joule) rating of a strobe has NOTHING to do with the amount of light coming out of it. It's a spec that measures the electrical energy stored in the capacitor bank that can be discharged through the flash tube. The efficiency of the path between the power bank and the tube and the luminous efficiency of the tube itself determine how much of that electrical energy is actually converted to photons. Two strobes with identical Joule ratings can have significantly different light outputs if one is, say, an antique cold-war era design and the other is a modern high-efficiency IGBT design. Similarly, you can get identical light output from two different input power ratings if the efficiency of the designs is quite different.

edit: I see. You've got the Lumu, too. Can you provide a link to the Illuminati meter you've purchased? Our needs overlap, and I can only find it as a pre-order Kickstarter kind of thing.

The Illuminati meter was a Kickstarter. It just started shipping to backers this week. I'm hoping I get mine by the end of the year but the holiday may screw that up. I have no idea when they expect to begin normal retail sales.




  
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williaty
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Dec 19, 2017 17:47 |  #40

jlafferty wrote in post #18521398 (external link)
I shoot dancers a lot. Hair, finger tips, edges of wardrobe... tack harp is 1/5000 minimally.

Measured or claimed duration? T.5 or T.1?

We each can only report what we observe. I'm getting reliably sharp dancers in mid-air at a measured t.1 around 1/2000 on a D810 with the dancer filling the frame.

If your 1/5000th is a t.1 claimed spec, maybe it actually measures closer to a 1/2000 t.1. If your 1/5000th spec is a t.5 duration, then that's probably somewhere in the realm of 1/1600th t.1, which then matches what I'm saying pretty closely.




  
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Robertk2012
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Dec 19, 2017 19:44 |  #41

T.1 or t.5?

jlafferty wrote in post #18521398 (external link)
I shoot dancers a lot. Hair, finger tips, edges of wardrobe... tack harp is 1/5000 minimally.





  
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Robertk2012
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Dec 19, 2017 19:47 |  #42

Should have read all of the way the down before replying...1/2000 is sharp and I have my work blown up to 8 ft or more.

williaty wrote in post #18522105 (external link)
Measured or claimed duration? T.5 or T.1?

We each can only report what we observe. I'm getting reliably sharp dancers in mid-air at a measured t.1 around 1/2000 on a D810 with the dancer filling the frame.

If your 1/5000th is a t.1 claimed spec, maybe it actually measures closer to a 1/2000 t.1. If your 1/5000th spec is a t.5 duration, then that's probably somewhere in the realm of 1/1600th t.1, which then matches what I'm saying pretty closely.




  
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jlafferty
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Post edited 5 months ago by jlafferty.
     
Dec 19, 2017 20:19 as a reply to  @ williaty's post |  #43

I'm saying shutter speed at 1/5000th for tack sharp dancers :)

Thanks for all your additional info!


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jlafferty
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Post edited 5 months ago by jlafferty. (2 edits in all)
     
Dec 19, 2017 20:22 |  #44

williaty wrote in post #18522100 (external link)
No electrical input power measurements were made (as there's no way to do so). The full power data point for the Xplor is plotted at 600J because that's what the manufacturer claims it is. If you don't trust them, take it apart and count the caps. Your comparison with the B800 is also somewhat meaningless...

It's not meaningless if your interest is in knowing how lights perform relative to each other vs. declaring some arbitrary watt-second claim to be true, disconnected from context. I put the light in the same modifier and measured the output at the same distance. For my purposes this is the only measurement of meaning.


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dpe
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Dec 20, 2017 02:13 |  #45

jlafferty wrote in post #18522218 (external link)
It's not meaningless if your interest is in knowing how lights perform relative to each other vs. declaring some arbitrary watt-second claim to be true, disconnected from context. I put the light in the same modifier and measured the output at the same distance. For my purposes this is the only measurement of meaning.

Then as has been said you are not measuring watt/s but real life use which is filled with so many variables it is confusing as one 90cm Octa performs very differently from another 90cm octa for example


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Results of Flash Duration Measurements on My Various Strobes
FORUMS General Gear Talk Flash and Studio Lighting 
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