Brent Ward wrote: Paul Buff wrote:
1/22,000 is the t.5 time it would take from a non IGBT flash to get a 1/7000 t.1. But the IGBT controlled motion freezing is much better than equivalent non IGBT t.1.
The reason is, on a conventional system there is still 1/10 of the total power emitted after the t.1 one time. This is just under -3 f stops and goes on for a long time. Thus, bright objects can still show some blur that belies the stated t.1 time. On Einstein, there is nothing after the t.1 time so action freezing is much sharper. Ask Rob Galbraith about this - he\'s the preeminent expert.
The two systems you mention are IGBT controlled. I have no idea why Profoto would publish t.5 times on an IGBT system?? If I want to play that game Einstein would come out about 1/20,000 t.5 . . . or as high at 1/30,000 if I want to ignore solid performance in order to create a real fast number. Or I could change the fill pressure n the tubes and get it up to 1/50,000 at a cost of reliability. Would yawl rather see that number? Would it make you think my product suddenly became light years faster and better?
I have to disagree that 1/8000 t.1 and 1/12,000 are equal on IGBT systems. 1/8000 t.1, if you measure it and understand the technology, will come out abut 1/15,000 t.5.
BTW, you can\'t measure IGBT t.1 or t.5 times using the old methods. You must use true RMS integration of light VS time. I have developed test equipment to do just that and can guarantee and verify my numbers..
This is an opportunity for the industry to clarify this so users can compare and understand. I will do that . . . if others want to keep manipulating numbers . . . they\'ll be gone in 60 seconds.
I have published Lumenseconds for years while others keep talking about meaningless guide numbers and assigned new non-dictionary definitions of the word range and any number of other marketing hypes.
I\'m not sure why profoto does that either. I called them once, they didn\'t even know the t.1 times. Thanks for the explanation!
Wow . . . really professional!. All customer service peeps at Buff know the difference and implications. My guess is they are using gate turnoff time (somewhat longer than real t.1, and just expressing it as t.? You can determing t.5 on an IGBT flash by the old methods . . . you have to determine, on an RMS basis, what time it takes to emit 50% of the total.
For anyone who is determining t.5 and t.1 times by the 50% and 10% points on a captured waveform, the is archaic . . . poor accuracy on conventional flash and meaningless on IGBT flash. I have developed a precision method that integrates the actual light over time (same thing a camera does) and instantly gives you exact t,5, t.1 or t. anything else . . . like t.125 or whatever, on conventional or IGBT.
Maybe when I get time I will incorporate this into an inexpensive flashmeter. But please don\'t start asking for it yet - I\'m exhausted.
Brent Ward wrote: Paul Buff wrote:
1/22,000 is the t.5 time it would take from a non IGBT flash to get a 1/7000 t.1. But the IGBT controlled motion freezing is much better than equivalent non IGBT t.1.
The reason is, on a conventional system there is still 1/10 of the total power emitted after the t.1 one time. This is just under -3 f stops and goes on for a long time. Thus, bright objects can still show some blur that belies the stated t.1 time. On Einstein, there is nothing after the t.1 time so action freezing is much sharper. Ask Rob Galbraith about this - he\'s the preeminent expert.
The two systems you mention are IGBT controlled. I have no idea why Profoto would publish t.5 times on an IGBT system?? If I want to play that game Einstein would come out about 1/20,000 t.5 . . . or as high at 1/30,000 if I want to ignore solid performance in order to create a real fast number. Or I could change the fill pressure n the tubes and get it up to 1/50,000 at a cost of reliability. Would yawl rather see that number? Would it make you think my product suddenly became light years faster and better?
I have to disagree that 1/8000 t.1 and 1/12,000 are equal on IGBT systems. 1/8000 t.1, if you measure it and understand the technology, will come out abut 1/15,000 t.5.
BTW, you can\'t measure IGBT t.1 or t.5 times using the old methods. You must use true RMS integration of light VS time. I have developed test equipment to do just that and can guarantee and verify my numbers..
This is an opportunity for the industry to clarify this so users can compare and understand. I will do that . . . if others want to keep manipulating numbers . . . they\'ll be gone in 60 seconds.
I have published Lumenseconds for years while others keep talking about meaningless guide numbers and assigned new non-dictionary definitions of the word range and any number of other marketing hypes.
I\'m not sure why profoto does that either. I called them once, they didn\'t even know the t.1 times. Thanks for the explanation!
Wow . . . really professional!. All customer service peeps at Buff know the difference and implications. My guess is they are using gate turnoff time (somewhat longer than real t.1, and just expressing it as t.? You can determing t.5 on an IGBT flash by the old methods . . . you have to determine, on an RMS basis, what time it takes to emit 50% of the total.
For anyone who is determining t.5 and t.1 times by the 50% and 10% points on a captured waveform, the is archaic . . . poor accuracy on conventional flash and meaningless on IGBT flash. I have developed a precision method that integrates the actual light over time (same thing a camera does) and instantly gives you exact t,5, t.1 or t. anything else . . . like t.125 or whatever, on conventional or IGBT.
Maybe when I get time I will incorporate this into an inexpensive flashmeter. But please don\'t start asking for it yet - I\'m exhausted.
Jan 07, 2010 at 09:39 PM
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