Archive 2010 · Vagabond Mini Lithium
p.15 #1Vagabond Mini Lithium
RustyBug wrote:
ooops!!!
... forgot about the gas vs. filament. (Won't a change in voltage through the gas still render a different result?)
Wikipedia has a nice writeup on this topic, and it's trickier than I thought. The spectrum is indeed affected by amperage but, for flash tubes in photo applications, the spectrum is not simply black body. The effective color temperature is influenced by spectral lines from the particular gas (Xenon in our case).
Ref:
http://en.wikipedia.org/wiki/Flashtube
ooops!!!
... forgot about the gas vs. filament. (Won't a change in voltage through the gas still render a different result?)Wikipedia has a nice writeup on this topic, and it's trickier than I thought. The spectrum is indeed affected by amperage but, for flash tubes in photo applications, the spectrum is not simply black body. The effective color temperature is influenced by spectral lines from the particular gas (Xenon in our case).
Ref:
http://en.wikipedia.org/wiki/Flashtube
Sep 21, 2010 at 05:06 PM
p.15 #2Vagabond Mini Lithium
"but I'll still miss his technical interaction (I obviously need it more than most) "
ditto. he would at least qualify his statements with technical know-how.
ditto. he would at least qualify his statements with technical know-how.
Sep 21, 2010 at 06:22 PM
p.15 #3Vagabond Mini Lithium
RustyBug wrote:
(Won't a change in voltage through the gas still render a different result?)
Yes, it will. That's why different types of output control have such different results.
Some strobes change the output by varying the voltage, others by using a constant voltage but varying the amount of time that the voltage is applied.
(Won't a change in voltage through the gas still render a different result?)
Yes, it will. That's why different types of output control have such different results.
Some strobes change the output by varying the voltage, others by using a constant voltage but varying the amount of time that the voltage is applied.
Sep 21, 2010 at 08:08 PM
p.15 #4Vagabond Mini Lithium
rico wrote:
... forgot about the gas vs. filament. (Won't a change in voltage through the gas still render a different result?)Wikipedia has a nice writeup on this topic, and it's trickier than I thought. The spectrum is indeed affected by amperage but, for flash tubes in photo applications, the spectrum is not simply black body. The effective color temperature is influenced by spectral lines from the particular gas (Xenon in our case).
Ref:
http://en.wikipedia.org/wiki/Flashtube
The physics of ionized Xenon gas discharge tubes are as follows: The color spectrum and flash duration are determined by arc length, gas fill pressure and applied voltage. Short arc length tubes with high fill pressure and high applied voltage produce very fast durations and extremely high color temperature (ala Edgerton).
For a typical studio flash tube that is designed to produce "daylight" color spectrum in the 5600°K range with Full power voltages typically between 300VDC and 900VDC, lowering the applied voltage will reduce power approximately based on Ohms Law (Power = Voltage squared/tube resistance) and results in a lowering of color temperature of typically 80°K per halving of power, and a lengthening of flash duration of approximately 20% per halving of power.
The process is not completely linear. Base flash duration can be optimized within a tube design. Very short duration tubes can be inefficient due to the power lost in the impedance of the flash capacitors and result in greater current flow through all the components, and will also have a shorter life span. The extreme currents can decrease the overall reliability.
My 30 years of research on these subjects conclude that, for a flash unit in the 600WS range, the optimal set of conditions . . . efficiency and reliability at short flash durations intersect at a full power t.5 flash duration in the 1/1500 to 1/2200 second range . . . typical for most high quality short duration pro flash units on the market. This range provides typical flashtube life of 250,000 to 1,000,000 flashes.
For further information, "t.5" indicates the time it takes for 1/2 of the available power to be dissipated while "t.1" indicates the time it takes to dissipate 90% of the available power. For a given non-IGBT system, the t.1 time is typically 3 times as long as the t.5 time. The t.1 time fairly closely resembles the action stopping capability in comparison to an equivalent camera exposure time using continuous light.
RustyBug wrote
ooops!!! ... forgot about the gas vs. filament. (Won't a change in voltage through the gas still render a different result?)Ref:
http://en.wikipedia.org/wiki/Flashtube
The physics of ionized Xenon gas discharge tubes are as follows: The color spectrum and flash duration are determined by arc length, gas fill pressure and applied voltage. Short arc length tubes with high fill pressure and high applied voltage produce very fast durations and extremely high color temperature (ala Edgerton).
For a typical studio flash tube that is designed to produce "daylight" color spectrum in the 5600°K range with Full power voltages typically between 300VDC and 900VDC, lowering the applied voltage will reduce power approximately based on Ohms Law (Power = Voltage squared/tube resistance) and results in a lowering of color temperature of typically 80°K per halving of power, and a lengthening of flash duration of approximately 20% per halving of power.
The process is not completely linear. Base flash duration can be optimized within a tube design. Very short duration tubes can be inefficient due to the power lost in the impedance of the flash capacitors and result in greater current flow through all the components, and will also have a shorter life span. The extreme currents can decrease the overall reliability.
My 30 years of research on these subjects conclude that, for a flash unit in the 600WS range, the optimal set of conditions . . . efficiency and reliability at short flash durations intersect at a full power t.5 flash duration in the 1/1500 to 1/2200 second range . . . typical for most high quality short duration pro flash units on the market. This range provides typical flashtube life of 250,000 to 1,000,000 flashes.
For further information, "t.5" indicates the time it takes for 1/2 of the available power to be dissipated while "t.1" indicates the time it takes to dissipate 90% of the available power. For a given non-IGBT system, the t.1 time is typically 3 times as long as the t.5 time. The t.1 time fairly closely resembles the action stopping capability in comparison to an equivalent camera exposure time using continuous light.
Sep 21, 2010 at 10:49 PM
p.15 #5Vagabond Mini Lithium
BrianO wrote:
Yes, it will. That's why different types of output control have such different results.
Some strobes change the output by varying the voltage, others by using a constant voltage but varying the amount of time that the voltage is applied.
Only IGBT controlled units can control the time the voltage is applied.
Capacitor switching is usually used in power pack systems to reduce power, often in conjunction with varying the voltage for fine tuning. If one reduces the capacitance in half one can expect the flash duration to be twice as fast and the color to remains essentially the same. However, as capacitance is reduced, the internal impedance of the flash capacitors dissipates more and more of the available power, so efficiency and flash durations deviate from a linear curve.
RustyBug wrote
(Won't a change in voltage through the gas still render a different result?)Some strobes change the output by varying the voltage, others by using a constant voltage but varying the amount of time that the voltage is applied.
Only IGBT controlled units can control the time the voltage is applied.
Capacitor switching is usually used in power pack systems to reduce power, often in conjunction with varying the voltage for fine tuning. If one reduces the capacitance in half one can expect the flash duration to be twice as fast and the color to remains essentially the same. However, as capacitance is reduced, the internal impedance of the flash capacitors dissipates more and more of the available power, so efficiency and flash durations deviate from a linear curve.
Sep 21, 2010 at 11:02 PM
p.15 #6Vagabond Mini Lithium
Paul Buff wrote:
Only IGBT controlled units can control the time the voltage is applied.
What about thyristors as used in some hotshoe flashes? How do they work?
Only IGBT controlled units can control the time the voltage is applied.
What about thyristors as used in some hotshoe flashes? How do they work?
Sep 22, 2010 at 01:12 AM
p.15 #7Vagabond Mini Lithium
a quick question about the mini. Will it have a strap so it can be carried on your shoulder like the older vbs?
Sep 22, 2010 at 01:27 AM
p.15 #8Vagabond Mini Lithium
BrianO wrote:
What about thyristors as used in some hotshoe flashes? How do they work?
They work like Einstein. IGBT switching is easy at the power levels and longer flash durations used in hotshoe flashes. Current and voltage is much smaller so a single low power IGBT can be used. We have to use multiple high power IGBTs. These were not readily available and very expensive until recently. Photogenic Studio Max uses IGBTs, but they are way long flash duration in order to avoid expensive multiple IGBTs. Long flash duration eases the current load on IGBTs. We are switching close to 2000 amps . . . takes big IGBTs.
Paul Buff wrote
Only IGBT controlled units can control the time the voltage is applied.They work like Einstein. IGBT switching is easy at the power levels and longer flash durations used in hotshoe flashes. Current and voltage is much smaller so a single low power IGBT can be used. We have to use multiple high power IGBTs. These were not readily available and very expensive until recently. Photogenic Studio Max uses IGBTs, but they are way long flash duration in order to avoid expensive multiple IGBTs. Long flash duration eases the current load on IGBTs. We are switching close to 2000 amps . . . takes big IGBTs.
Sep 22, 2010 at 01:37 AM
p.15 #9Vagabond Mini Lithium
alexisgc33 wrote:
a quick question about the mini. Will it have a strap so it can be carried on your shoulder like the older vbs?
Yes, it has a shoulder strap and we are working on a nice optional carry bag . . . should have it about the same time as Mini.
a quick question about the mini. Will it have a strap so it can be carried on your shoulder like the older vbs?
Yes, it has a shoulder strap and we are working on a nice optional carry bag . . . should have it about the same time as Mini.
Sep 22, 2010 at 01:38 AM
p.15 #10Vagabond Mini Lithium
Paul Buff wrote:
Yes, it has a shoulder strap and we are working on a nice optional carry bag . . . should have it about the same time as Mini.
Cool.. that's awesome!!
I'm sure whatever you come up will be cool. But please try to keep in mind, conservative dark colors for the optional carry bag. The florescent bright colors for example on the VBII just stream for attention or "steal me" I'm easy to find when your stashing your VBII in a corner w/ some extra gear at a wedding.
Cannot wait until this is out
alexisgc33 wrote
a quick question about the mini. Will it have a strap so it can be carried on your shoulder like the older vbs?Cool.. that's awesome!!
I'm sure whatever you come up will be cool. But please try to keep in mind, conservative dark colors for the optional carry bag. The florescent bright colors for example on the VBII just stream for attention or "steal me" I'm easy to find when your stashing your VBII in a corner w/ some extra gear at a wedding.
Cannot wait until this is out
Sep 22, 2010 at 02:59 AM
p.15 #11Vagabond Mini Lithium
The t.1 time fairly closely resembles the action stopping capability in comparison to an equivalent camera exposure time using continuous light.
BINGO !!!
Now, THAT is something to hang on to ... will be VERY useful when working outdoors and mixing with ambient.
Paul, thanks for the explanation ... very clarifiying, not that I'll remember it all.
(but I can always come back to the thread for review, cool)
Nice ... will the bag have provisions for extras ... like storage for two VBM's or a second / third battery?
BINGO !!!
Now, THAT is something to hang on to ... will be VERY useful when working outdoors and mixing with ambient.
Paul, thanks for the explanation ... very clarifiying, not that I'll remember it all.
(but I can always come back to the thread for review, cool)
Nice ... will the bag have provisions for extras ... like storage for two VBM's or a second / third battery?
Sep 22, 2010 at 08:36 AM
p.15 #12Vagabond Mini Lithium
BrianO wrote:
...Some strobes change the output by varying the voltage, others by using a constant voltage but varying the amount of time that the voltage is applied.
Paul Buff wrote:
Only IGBT controlled units can control the time the voltage is applied.
BrianO wrote:
What about thyristors as used in some hotshoe flashes? How do they work?
Paul Buff wrote:
They work like Einstein.
So then IGBTs are NOT the only way, right?
...Some strobes change the output by varying the voltage, others by using a constant voltage but varying the amount of time that the voltage is applied.
Paul Buff wrote:
Only IGBT controlled units can control the time the voltage is applied.
BrianO wrote:
What about thyristors as used in some hotshoe flashes? How do they work?
Paul Buff wrote:
They work like Einstein.
So then IGBTs are NOT the only way, right?
Sep 23, 2010 at 01:44 AM
p.15 #13Vagabond Mini Lithium
BrianO wrote:
So then IGBTs are NOT the only way, right?
Capacitor switching is also possible. Turning off and on banks of capacitors instead off lowering voltage. Profoto uses this in combined with voltageregulation in their more expensive packs that's why you see a huge drop in K till you reach a full stop. WL X1600, X3200 carry this function too with a manual switch while profoto I believe have this integraded into the power variator.
BrianO wrote
...Some strobes change the output by varying the voltage, others by using a constant voltage but varying the amount of time that the voltage is applied.Paul Buff wrote
Only IGBT controlled units can control the time the voltage is applied.BrianO wrote
What about thyristors as used in some hotshoe flashes? How do they work?Paul Buff wrote
They work like Einstein.Capacitor switching is also possible. Turning off and on banks of capacitors instead off lowering voltage. Profoto uses this in combined with voltageregulation in their more expensive packs that's why you see a huge drop in K till you reach a full stop. WL X1600, X3200 carry this function too with a manual switch while profoto I believe have this integraded into the power variator.
Sep 23, 2010 at 04:26 AM
p.15 #14Vagabond Mini Lithium
BrianO wrote:
So then IGBTs are NOT the only way, right?
Capacitor switch will shorten durations but with two caveats:
1. It is pretty much limited to full f stop changes and not practical for fine adjustments like 1/10f or even 1/3f.
2. It retains the tapered "tail", So a t.1 time of, say 1/2000 still has 10% of the energy left following the 1/2000 second period. 10% of the energy equates to -3.2f stops below peak energy. It takes another 1/666 second for the tail to fall to -6f. (t,03) So if you are shooting sports for instance, with a white ball, at 1/2000 second the ball is still illuminated sufficiently to produce considerable motion blur when compared to a true exposure time of 1/2000.
IGBT switching absolutely shuts the tail off, so for an equal t.1 time, the IGBT unit will stop action considerably cleaner than a capacitor switched unit,
BrianO wrote
...Some strobes change the output by varying the voltage, others by using a constant voltage but varying the amount of time that the voltage is applied.Paul Buff wrote
Only IGBT controlled units can control the time the voltage is applied.BrianO wrote
What about thyristors as used in some hotshoe flashes? How do they work?Paul Buff wrote
They work like Einstein.Capacitor switch will shorten durations but with two caveats:
1. It is pretty much limited to full f stop changes and not practical for fine adjustments like 1/10f or even 1/3f.
2. It retains the tapered "tail", So a t.1 time of, say 1/2000 still has 10% of the energy left following the 1/2000 second period. 10% of the energy equates to -3.2f stops below peak energy. It takes another 1/666 second for the tail to fall to -6f. (t,03) So if you are shooting sports for instance, with a white ball, at 1/2000 second the ball is still illuminated sufficiently to produce considerable motion blur when compared to a true exposure time of 1/2000.
IGBT switching absolutely shuts the tail off, so for an equal t.1 time, the IGBT unit will stop action considerably cleaner than a capacitor switched unit,
Sep 23, 2010 at 11:09 AM
p.15 #15Vagabond Mini Lithium
Okay, so capacitor switching, IGBTs, and thyristors can all curtail the flash based on time, rather than changing voltage, but each has a different way of handling the details.
Sep 23, 2010 at 11:04 PM
p.15 #16Vagabond Mini Lithium
BrianO wrote:
Okay, so capacitor switching, IGBTs, and thyristors can all curtail the flash based on time, rather than changing voltage, but each has a different way of handling the details.
Correct. Almost all monolights use voltage control, with some like WLX combining cap switching and voltage control. Most power packs primarily use cap switching but augment it with voltage control for fine tuning. All speedlights use low power IGBT switching, which provides the greatest control of color and duration. It's necessary for TTL and HSS functions. Top end packs like Grafit, Scoro, etc us high power IGBTs, as does Einstein and Photogrenic Solair.
As mentioned, the sharp light cutoff of IGBTs results in cleaner and effectively shorter action stopping than equivalent t.1 times obtained from cap switching or voltage control.
IGBT flashes require a processor algorithm to vary charge voltage as power is adjusted to achieve constant color. Without the voltage control algorithm the color temperature rises dramatically as power is lowered . . . the opposite of voltage controlled flashes.
Einstein and ultra high end IGBT packs allow changing the voltage vs power algorithm to achieve either constant color or absolute minimum durations (at the cost of color getting bluer as power is lowered.) Einstein "action" algorithm allows color to rise from 5600°K up to about 6300° at low power to achieve 1/13,500 t.1 durations at reasonable color. Durations could be made even shorter with different algorithm but color would rise into the 10,000°K range. Einstein Color Mode holds color constant at 5600°K but still achieves 1/8000 second t,1 times at lower power settings.
See http://blog.bronimaging.com/2010/01/broncolor-scoro-enhanced-color-temperature-control-ectc/ for more explanation.
Okay, so capacitor switching, IGBTs, and thyristors can all curtail the flash based on time, rather than changing voltage, but each has a different way of handling the details.
Correct. Almost all monolights use voltage control, with some like WLX combining cap switching and voltage control. Most power packs primarily use cap switching but augment it with voltage control for fine tuning. All speedlights use low power IGBT switching, which provides the greatest control of color and duration. It's necessary for TTL and HSS functions. Top end packs like Grafit, Scoro, etc us high power IGBTs, as does Einstein and Photogrenic Solair.
As mentioned, the sharp light cutoff of IGBTs results in cleaner and effectively shorter action stopping than equivalent t.1 times obtained from cap switching or voltage control.
IGBT flashes require a processor algorithm to vary charge voltage as power is adjusted to achieve constant color. Without the voltage control algorithm the color temperature rises dramatically as power is lowered . . . the opposite of voltage controlled flashes.
Einstein and ultra high end IGBT packs allow changing the voltage vs power algorithm to achieve either constant color or absolute minimum durations (at the cost of color getting bluer as power is lowered.) Einstein "action" algorithm allows color to rise from 5600°K up to about 6300° at low power to achieve 1/13,500 t.1 durations at reasonable color. Durations could be made even shorter with different algorithm but color would rise into the 10,000°K range. Einstein Color Mode holds color constant at 5600°K but still achieves 1/8000 second t,1 times at lower power settings.
See http://blog.bronimaging.com/2010/01/broncolor-scoro-enhanced-color-temperature-control-ectc/ for more explanation.
Sep 23, 2010 at 11:45 PM
p.15 #17Vagabond Mini Lithium
Thanks again for the detailed information. Always appreciated.
Sep 24, 2010 at 12:14 AM
p.15 #18Vagabond Mini Lithium
Paul, I'm extremely curious and somewhat worried about potential glitching or crashing of a Profoto Compact300/600 or D1-500 power supply.
While I know that testing a non-house brand light is never a priority, I would very much like to know the compatibility. If you do come across these type of heads, please share your findings here, thanks!
While I know that testing a non-house brand light is never a priority, I would very much like to know the compatibility. If you do come across these type of heads, please share your findings here, thanks!
Oct 14, 2010 at 01:09 PM
p.15 #19Vagabond Mini Lithium
miccullen wrote:
Yes, absolute junk, that Profoto stuff. Garbage. Trash. No idea how they sell it.
Nor how you are getting away with posting this stuff, unbelievable.
Well, go out and test to see... Remember there was not a Canon 1DIII issue there for awhile.
Paul Buff wrote
I think you're absolutely on the wrong side of this issue. If Vag mini can power 1200WS of Elinchrom and 2500WS worth of Buff lights, the fact the "premiere" Profoto can't even run one 300WS unit makes there engineering extremely suspect.Nor how you are getting away with posting this stuff, unbelievable.
Well, go out and test to see... Remember there was not a Canon 1DIII issue there for awhile.
Oct 15, 2010 at 05:52 PM
p.15 #20Vagabond Mini Lithium
"In the mean time I too would like to see an independent test of the mini vagabond with the following lights:'
I would too when it exists and when it's delivered. I'll be one of the first to buy one if it's any good.
"Do it right and In six or seven years you too can be as wealthy as Fred Miranda, or maybe even Mr. Buff."
What makes you think I'm not already? Pretty condescending Ellis. I'm sure Mr. Miranda appreciates you telling his paying customers to leave and go somewhere else. Great for business.
I would too when it exists and when it's delivered. I'll be one of the first to buy one if it's any good.
"Do it right and In six or seven years you too can be as wealthy as Fred Miranda, or maybe even Mr. Buff."
What makes you think I'm not already? Pretty condescending Ellis. I'm sure Mr. Miranda appreciates you telling his paying customers to leave and go somewhere else. Great for business.
Oct 15, 2010 at 10:21 PM