Monolight flash duration

[Anton Largiader]

Playing around with some lights I think it never got on my radar that monolights had a pretty long duration compared to speedlights. Reading up on this a bit, I gather that monolights which charge to a variable voltage have a constant decay regardless of the power level, whereas IGBT controlled lights (mostly speedlights but this is changing) have the super short durations.

If this is true, then I think these Photogenic PL-1250s (and other models that I have available) may be fundamentally unsuitable for action shots unless I am willing to live with fingertip and foot blur. IGBT lights like the Einstein would freeze this action better. OTOH, it doesn't look like IGBT options have the same power. In this case (the 500 W-s lights were at 1/4 to 1/2 power and the softbox was about 5' away) I probably could have just used a speedlight, but if I'm shooting in a larger space and needing to overpower more ambient then maybe not.

What does it take to stop action better in a studio setting? Is the fingertip blur to be expected with this kind of light?

This was f/11, 1/125, ISO 100. I'm pretty sure the ambient exposure was totally dark, based on the preview, but I can double check that this evening when the ambient is the same.

 

[ImageMaker]

1/5000 shutter speed using Elinchroms HS trigger

 

[Anton Largiader]

It would help if you used some words, but are you inferring that HSS is a good avenue to explore? What triggering would work with which lights for me? Any issues with mixing lights, and how much power might I get outdoors for this?

 

[Arbby]

This page https://www.thebroketographers.com/...h-duration-analysis-for-godoxflashpoint-ad600 lists measured and claimed flash durations against power setting for the Godox AD600 which is typical of IBGT controlled strobes. Some more expensive options might be a bit faster. If you are looking at specs make sure you understand the difference between t0.1 and t0.5.

To freeze action with flash you need to limit power output which means even bigger strobes if you need more light.

You can investigate motion blur just using shutter speed and ambient light to get an idea of what flash duration you are going to want.

Addition: HSS is terrible for freezing motion compared to short duration flash. The only reason to use it is when you have enough ambient to produce too much of an image at camera shutter sync speed.

 

[Anton Largiader]

The only time I see posted for the PL1250 is 1/1300 s, which I have to assume is the t0.5 time. The blur I'm seeing on the fingertips is, to my eye, faint enough that it's going to be from the light after the t.05 is over. I wish the guy in your link above tested the t0.1 on the PL1250. From links I read previously, it sounds like it's typically 3~4 times t0.5? From past experience shooting runners, that would make the flash long enough to get motion blur.

> This discussion < (link) deals directly with the PL1250 and motion blur. Sounds like I need to start looking at IGBT products.

 

[ImageMaker]

It would help if you used some words, but are you inferring that HSS is a good avenue to explore? What triggering would work with which lights for me? Any issues with mixing lights, and how much power might I get outdoors for this?

No, not HSS, HS (Hi-sync) which differs from HSS. Takes a “normal” yet slower burning flash while shutter speed can be increased.

Elinchrom uses(d?) this method and has a trigger that aids in the timing to maintain flash during high shutter speeds. There are compatibility charts showing which strobe supports this. Hummingbirds in the photo above don’t fly at night. It was 6pm in the shade. Ambient light was easily overpowered by the flash at 1/5000 f5.6

The obvious option is to use a strobe that has a flash speed at the power you desire. With Elinchroms ELC monolights they publish a power/flash speed chart.

 

[Anton Largiader]

Ah, Hypersync. Got it. My triggers (PW TT1 and TT5) have that but I'm unclear on what is supported on the newer Canon cameras. I've been meaning to do some reading on this so maybe this is the time. Seems it will still give up some total power, though, if you're only making use of the brightest part of the flash.

I have these lights on loan, and at some point need to decide what to buy. Ideally I would find some battery-power strobes, so if I'm buying something different it may as well be IGBT.

 

[Anton Largiader]

So, comparing technology options here I see this:

1) Conventional strobes at X-sync: slower burn, easy to adjust, you get all of the power they can produce, as long as you don't need to stop motion. Limited to X-sync so ambient can be an issue.

2) Conventional strobes with HS: you can stop motion with the shutter but you lose max power, and you need some sort of HS controller like Raven or Transmitter Pro that communicates with your camera using more than just the center pin (usually with the E-TTL info). May be hard to mix different products. For instance I use my speedlight with the PL1250s and it's possible the speedlight flash would be over by the time the shutter opens for HS. But maybe that can be tuned out, since I use the speedlight on a TT-5. Within the power you have available, you can reduce the ambient.

3) IGBT strobes at X-sync: Stop motion with the flash very well once you reduce power a little bit, but might not play well with X-sync if needed since the initial intensity is the same regardless of power level. It sounds like color variation issues with IGBTs (colder at the top of the curve and warmer toward the end) are corrected for by the manufacturers of these products.

Do I have this about right?

 

[Wilt]

Generally speaking, higher power = longer duration of light, no matter if speedlight or studio flash. For example

• Metz 64AF-1 speedlight: duration 1/750 at 1/1 or 1/2, 1/7500 at 1/16, 1/40000 at 1/256
• Canon 600EX speedlight: 1/555 (1.8ms Canon spec) or less (no explicit statement from Canon)
• Dynalite M2000 studio flash: 1/700 single head at full power, 1/3800 using 2 heads at minimum power
• Balcar A3200 studio flash: 1/700 at full power, 1/8000 minimum
• Godox DPIIIV monolights: 1/800 at full power, 1/2000 minimum
• Profoto D2 monolight: 1/1000 at 500 w-s, 1/7700 at 1 w-s (t0.1 in 'normal mode')

With studio lights, reduce power level to shorten duration, and split the stored power into more than one flash tube. Some units have 'bi-tube head' that puts two flashtubes in the single head, made for the purpose of shorter duration light output.
Speedlights do not necessarily have really short durations at full power...note the durations shown for the two speedlights listed.

I consider comparison of t0.5 vs. t0.1 nothing but specmanship...if the camera shutter is open for 1/250 (the X-sych speed of typical pro level dSLR) it will capture the ENTIRE output (1/1000 for the Profoto) from the flash tube, as the flash tube does not cut off its output after the t0.5 time (1/2600 for the Profoto), does it?!

​

 

[Anton Largiader]

I think by pretending the t0.5 and t0.1 difference isn't meaningful, you're missing the whole point. All of the times you cited are going to be specifically one or the other (usually t0.5) and the other value is quite different, and a lot of light comes out between those two times. So the duration isn't nearly a simple number. And yes the X-sync shutter captures the whole output... that's the entire problem! If it weren't for all of that dying light between t0.5 and t0.1, I probably wouldn't have noticed any blur. But it's there, so either the light needs to be shorter (favors IGBT, which generally has no long tail) or the shutter needs to be shorter (favors VV and HS).

If you haven't tried to stop motion with studio strobes, you might never encounter this. The blurred hand in the image above isn't something I want to HAVE to accept.

BTW the 600EX-RT was measured at 1/355 to t0.1 in the test, whereas Canon's 1/555 claim is probably to t0.5. But even that longer t0.1 time probably (because it's IGBT) dropped off dramatically even with -1/3 stop adjustment. I wish they'd tested at smaller increments between 1/2 and full power for the IGBT strobes. I'm talking about the tests on -> this page <-which you can get to from one of the pages previously mentioned.

 

[Anton Largiader]

Exploring the HS (not HSS) avenue for the moment, what triggers are available for Canon mirrorless that would give me HS flash? I could get that on DSLRs with my PocketWizard TT1/TT5 combo, but PW is pretty clear that this does not work on the mirrorless cameras. I don't know why it wouldn't, if the TT1 is emulating the same flash that it emulated on the DSLRs, but I don't doubt what they say. The TT5 can be a receiver with mirrorless but none of those TT1/5/6 products can be a ControlTL transmitter.

PW does sell the Raven, which looks like a fully capable flash controller, complete with graphic visualization of flash timing. It's not particularly cheap at $370, but if it lets me use these old strobes and existing triggers to shoot fast, it's a worthwhile option to consider.*

The Godox XProC seems to be a similar product, and far less expensive. From the sounds of it, it won't trigger my existing Plus2 and TT5 receivers, but a set of Godox triggers aren't that expensive. And if that would allow me to wirelessly control the output of my 430EXii, it would be a nice little benefit. User reviews say it doesn't do TTL and HSS, but if it's just that particular combo then it's not a problem.

Elinchrom and Profoto have their own systems as well.

* EDIT: no, I can't use the Raven to trigger my Plus2s. I can trigger my TT5 with it if I upgrade the TT5 firmware, but then the TT5 won't work with the TT1. And the TT1/TT5 is a really nice combo for remote flash, even though it has to be manual with the mirrorless models. I will probably leave all of the PW stuff working together under the older firmware and look at a different solution for any faster flash.

 

[ImageMaker]

I have several Elinchrom Ranger RX AS Speed 1,100 ws battery powered head and pack units. With the standard S heads and the Elinchrom Pro trigger, it supports shutter speeds up to 1/8000 second without quality issues. Freezes movement well and supports shooting at wide apertures. 1.4-2.8

This photo used the sun as a backlight, Ranger RX AS Speed as main, darkened the valley behind to taste at 1/2000 at appx f3.1

 

[Sincity]

I have several Elinchrom Ranger RX AS Speed 1,100 ws battery powered head and pack units. With the standard S heads and the Elinchrom Pro trigger, it supports shutter speeds up to 1/8000 second without quality issues. Freezes movement well and supports shooting at wide apertures. 1.4-2.8

This photo used the sun as a backlight, Ranger RX AS Speed as main, darkened the valley behind to taste at 1/2000 at appx f3.1

I have a similar setup with the Ranger RX, but I am using the really fast "A" or Action heads. And I have seen people getting 1/4300 durations at the 33% socket. I have some sports photographers who are shooting arenas with Elinchrom and getting really good results... They are able to get with 1,000 watt-seconds power with 1/3000 ; 500 w/s at 1/5000 and so forth...

To the OP of the thread.. Have you looked at Konsul Instruments and their findings...

https://www.konsul-instruments.com/en/flash-duration-meter/

 

[Wilt]

I think by pretending the t0.5 and t0.1 difference isn't meaningful, you're missing the whole point. All of the times you cited are going to be specifically one or the other (usually t0.5) and the other value is quite different, and a lot of light comes out between those two times. So the duration isn't nearly a simple number. And yes the X-sync shutter captures the whole output... that's the entire problem! If it weren't for all of that dying light between t0.5 and t0.1, I probably wouldn't have noticed any blur. But it's there, so either the light needs to be shorter (favors IGBT, which generally has no long tail) or the shutter needs to be shorter (favors VV and HS).

If you haven't tried to stop motion with studio strobes, you might never encounter this. The blurred hand in the image above isn't something I want to HAVE to accept.

BTW the 600EX-RT was measured at 1/355 to t0.1 in the test, whereas Canon's 1/555 claim is probably to t0.5. But even that longer t0.1 time probably (because it's IGBT) dropped off dramatically even with -1/3 stop adjustment. I wish they'd tested at smaller increments between 1/2 and full power for the IGBT strobes. I'm talking about the tests on -> this page <-which you can get to from one of the pages previously mentioned.

What I meant by 'specsmanship' was that the t0.5 time vs. t0.1 time itself, unless it was controllable somehow by the user (setting 't0.1' vs. tsetting 't0.5' for change in output characterists) to shorten the output time of the light from the flash unit, the shutter is always getting 1/250 light duration. That is why my prior post ended with wondering if it were possible on the Profoto to CHOOSE which duration.
The as-shot difference would certainly be less hand-motion blur of a rapidly waving hand with a flash that has the bulk of its output within the t0.1 time with its very rapid fall-off of intensity rather than stretching a significant portion out to the t0.5 time and its slower falloff of intensity.

 

[Anton Largiader]

Let's define some of this stuff, just so we're all on the same page.

t0.5 (also written t.5) is the time needed for a capacitor to discharge down to half of its starting power. The .5 means that there is .5 (50%) of the power left. t.1 is the time needed to discharge down to 10% power left, so it's longer (it needs to discharge 90% of the load, and given that it's an asymptotic decay it takes disproportionally longer). Paul C Buff illustrates this here: https://www.paulcbuff.com/Flash-Duration.html

I'm not sure what you mean by setting or choosing one or the other; as far as I know they are fixed characteristics of a strobe design. Do you mean, let's say you ask for 200 Ws and you can get it at t.5 with one power setting and t.1 with a lower one? That would be true but I'm not sure it would be useful, since as we both say the camera is receiving the t.1 light no matter what. I think more useful is to know whether the number you are reading and comparing is a t.5 or a t.1 measurement. Anyone who wants to stop action wants to compare t.1 numbers, because by the time t.1 rolls around the light is pretty much over. Not the case at the shorter t.5; there is still (by definition) 40% of the light still to come before t.1 rolls around. That's a lot. So when a strobe maker tells you his light has a 1/600 duration but half of the light is still coming out after that, but before your 1/200 exposure is over, that is what this is all about.

These really only apply to full discharges. As you can see by PCB's graphs, IGBTs usually (as long as the power is turned down a bit) truncate that whole tail where t.1 happens so t.1 is mostly not even applicable to IGBTs. But by changing the power setting of an IGBT strobe you really are, in a way, choosing the duration. And in a much more definitive manner than changing the power of a variable voltage strobe.

 

[Wilt]

Let's define some of this stuff, just so we're all on the same page.

t0.5 (also written t.5) is the time needed for a capacitor to discharge down to half of its starting power. The .5 means that there is .5 (50%) of the power left. t.1 is the time needed to discharge down to 10% power left, so it's longer (it needs to discharge 90% of the load, and given that it's an asymptotic decay it takes disproportionally longer). Paul C Buff illustrates this here: https://www.paulcbuff.com/Flash-Duration.html

I'm not sure what you mean by setting or choosing one or the other; as far as I know they are fixed characteristics of a strobe design. Do you mean, let's say you ask for 200 Ws and you can get it at t.5 with one power setting and t.1 with a lower one? That would be true but I'm not sure it would be useful, since as we both say the camera is receiving the t.1 light no matter what. I think more useful is to know whether the number you are reading and comparing is a t.5 or a t.1 measurement. Anyone who wants to stop action wants to compare t.1 numbers, because by the time t.1 rolls around the light is pretty much over. Not the case at the shorter t.5; there is still (by definition) 40% of the light still to come before t.1 rolls around. That's a lot. So when a strobe maker tells you his light has a 1/600 duration but half of the light is still coming out after that, but before your 1/200 exposure is over, that is what this is all about.

These really only apply to full discharges. As you can see by PCB's graphs, IGBTs usually (as long as the power is turned down a bit) truncate that whole tail where t.1 happens so t.1 is mostly not even applicable to IGBTs. But by changing the power setting of an IGBT strobe you really are, in a way, choosing the duration. And in a much more definitive manner than changing the power of a variable voltage strobe.

Thx for the full explanation.

 

[Pictoraider]

This was f/11, 1/125, ISO 100. I'm pretty sure the ambient exposure was totally dark, based on the preview, but I can double check that this evening when the ambient is the same.

What about the rim light's flash duration ?

 

[Anton Largiader]

In my gymnast pic? That was my 430EXii so it was probably very short. I don't recall the power level I used, but full power on that has a really big effect in that setting so it had to be turned down quite a bit. It seems that Canon lists 1/350 for full power t.1 and 1/1630 for 1/2 power t.1. I don't see any blurring on the rim light on her hand, so I don't think there's any issue there. It was probably around half power or even less.

 

[Pictoraider]

The ghost image of the fingers superimposed on the overall sharp image, due to the fact that the extremities of the upper limbs move faster than the rest of the body, implies that there are two light sources in play. If it wasn't ambient light, because it was insignificant at f:11 and 1/125th s, it's worth investigating rim light. Imho.

To freeze movement (= about 1/1000th s), I have to set my 550EX to a quarter of its maximum power, or even less. Half power is not enough.
Regards,

PS: If the maximum synchro-X speed is 1/250th s, why only 1/125th s? You might as well display 1/250th s straight away.

 

[Anton Largiader]

I was probably in ES, so flash sync is 1/160. But with mechanical shutter it's only 1/200, not 1/250. I think only APS-C bodies can do 1/250. Still, you're right I had no reason to be less than 1/160 and could have been at 1/200 just as easily.

Here's a 100% crop of the hand. The rim light has a very narrow blur band, so I think it's pretty safe to say that it had a very short duration. The skin blur, harder to say. You have a point that it could be ambient, but I think it's very consistent with the hand moving downward as the flash dies out.