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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

 
Robertk2012
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Dec 20, 2017 04:58 |  #46

jlafferty wrote in post #18522215 (external link)
I'm saying shutter speed at 1/5000th for tack sharp dancers :)

Thanks for all your additional info!

We are talking about the equivalent shutter speed of the flash.




  
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jlafferty
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Post edited over 1 year ago by jlafferty. (2 edits in all)
     
Dec 20, 2017 08:04 |  #47

For my sake, it's not really confusing and I was aware of the nature of the slippery slope you're suggesting here. I think it's unnecessary and even counterproductive to have to detail this past a certain threshold - it reduces the process to satisfying academic standards and not photographic. If you dig around you can find evidence that Godox states that the AD360 for example is *exactly* 307ws. It just so happens it performs almost identically to a 310-320ws monolight from another manufacturer, measured at the same distance in the same style modifier (and FWIW bare bulb as well). Calling it a 300ws light, or saying "it performs like a 300ws light" is - in a real world context - a good general statement.

dpe wrote in post #18522329 (external link)
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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jlafferty
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Post edited over 1 year ago by jlafferty. (2 edits in all)
     
Dec 20, 2017 08:17 |  #48

Right. And I'm saying in either case… maybe 1/4000 but certainly 1/5000 in flash duration or shutter speed is the minimum to get ends of hair, shoe laces, etc. even skin detail completely frozen. 1/2000 doesn't cut it in my experience.

Of course… you have to factor in FOV & resolution so maybe where we're seeing differences is at the sensor. If distance, or subject-to-framing stays constant, my D700 is more forgiving than the D810; which is in turn more forgiving than the D850.

Robertk2012 wrote in post #18522349 (external link)
We are talking about the equivalent shutter speed of the flash.


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Robertk2012
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Dec 20, 2017 20:28 as a reply to  @ jlafferty's post |  #49

I’ll stick with my 1dx mk2 ߘ




  
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dmward
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Dec 22, 2017 22:04 |  #50

This is an interesting conversation.
One observation I'll make based on what an electrical engineer told me about a design spec we were working on for a telecommunications product.
"what we can do in the lab, and what a production device will do in day-to-day operation are different."
In the lab we have complete control over tolerances, and interworking between components. In the real world, the products are delivered based on manufacturing tolerances, which can vary quite a bit, and are subject to a wide range of installation parameters, all which can affect performance.

My personal level of confidence is 95+ for lab testing and 80- for day-to-day operation.


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Angmo
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Post edited over 1 year ago by Angmo. (2 edits in all)
     
Dec 23, 2017 09:20 |  #51

dmward wrote in post #18524380 (external link)
This is an interesting conversation.
One observation I'll make based on what an electrical engineer told me about a design spec we were working on for a telecommunications product.
"what we can do in the lab, and what a production device will do in day-to-day operation are different."
In the lab we have complete control over tolerances, and interworking between components. In the real world, the products are delivered based on manufacturing tolerances, which can vary quite a bit, and are subject to a wide range of installation parameters, all which can affect performance.

My personal level of confidence is 95+ for lab testing and 80- for day-to-day operation.

Effective use of six sigma tools will tighten things up to a great degree.

95 lab to 80 in production makes for lousy engineering, materials inspection, shop floor setup and quality control... Unless of course those are the specs to build the product.


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Wilt
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Post edited over 1 year ago by Wilt. (3 edits in all)
     
Dec 23, 2017 11:44 |  #52

Angmo wrote in post #18524587 (external link)
Effective use of six sigma tools will tighten things up to a great degree.

95 lab to 80 in production makes for lousy engineering, materials inspection, shop floor setup and quality control... Unless of course those are the specs to build the product.


It could simply be use of less expensive components, and in multiple places in the chain of components the tolerances stack in the wrong direction.
For example, for resistors a 'gold' tolerance band is 5% tolerance, 'silver' is 10%, and no band at all would mean a 20% tolerance.
For capacitors the actual capacitance is allowed to vary from its nominal value and can range anywhere from -20% to +80%, a 100µF capacitor with a ±10% tolerance could vary from 90µF to 110µF and still remain within tolerance, but a 100µF capacitor with a ±20% tolerance could legitimately vary from 80µF to 120µF and still remain within tolerance.


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Angmo
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Dec 23, 2017 12:07 |  #53

Wilt wrote in post #18524712 (external link)
It could simply be use of less expensive components, and in multiple places in the chain of components the tolerances stack in the wrong direction.
For example, for resistors a 'gold' tolerance band is 5% tolerance, 'silver' is 10%, and no band at all would mean a 20% tolerance.
For capacitors the actual capacitance is allowed to vary from its nominal value and can range anywhere from -20% to +80%, a 100µF capacitor with a ±10% tolerance could vary from 90µF to 110µF and still remain within tolerance, but a 100µF capacitor with a ±20% tolerance could legitimately vary from 80µF to 120µF and still remain within tolerance.

...and then there’s bi-directional diodes. ;-)a


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dmward
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Dec 23, 2017 14:14 |  #54

Angmo wrote in post #18524587 (external link)
Effective use of six sigma tools will tighten things up to a great degree.

95 lab to 80 in production makes for lousy engineering, materials inspection, shop floor setup and quality control... Unless of course those are the specs to build the product.

Six Sigma is a lot more hopeful thinking than reality.
I learned when building competition aircraft engines that I could use the tolerances, by stacking everything in one direction or another, to increase performance by a significant amount, while still being able to state it was a stock engine built to manufacturer's specs.

The reality is that electronic flash equipment is not likely to be Six Sigma and certainly they are going to decide on parts based on price rather than narrow tolerance.

And, mostly, as Wilt points out, there is never a guarantee that tolerances will average to the center as intended in the design spec.


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sincity
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Dec 23, 2017 14:36 as a reply to  @ dmward's post |  #55

I know it is gong way off topic with the six sigma and tolerances.. But the aerospace industry has moved on to a different standard from ISO 9001 to ISO 9100..

But with flash strobes and their measurements/ Measure-bations .. I don't think it would vary that much.. Tolerances have tightened up since the 1960s and the resistor color code. We now have SMD that are within .01% tolerances.




  
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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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