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Author Topic: Stopping motion with studio strobes and MFDB  (Read 15289 times)

godtfred

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Stopping motion with studio strobes and MFDB
« on: December 01, 2007, 07:23:53 pm »

I shoot people jumping and doing motion stuff from time to time, and even if I use my H2's top sync speed of 1/800, i seem to get a slight blur every time, the blur is the same, no matter what sync speed i use (unless it starts dipping below 1/80 or so, but I never go there unless i need it for effect.)

I don't get this on my canon 5D to the same degree, and have no explanation for it. I have speculated on these three possibilities:

1. The P45+ (previously H3D) has a larger resolution, and this somehow captures the blur more "clearly". I don't see why it should be like this, but a dealer brought this as an explanation.

2. I use one pack with pocketwizards, and let the other ones sync by the first packs flash burst. Effectively this would mean one pack flashes first, and all the others at the same time, but with a small delay behind the first. Could this be the culprit (and do i then need to buy a lot of pocketwizard recievers?)

3. My Profotos just don't have a short enough flash burst at medium power? (I use an Acute2 1200, a Pro-B and AcuteB600R, as well as some compacts if I need it.)

Anyone have the bullet proof recipie for motion stopping studio strobe use with a P45+ on a H2.

-axel
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Morgan_Moore

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« Reply #1 on: December 01, 2007, 07:34:53 pm »

Ideas

MF = slower ISO = more power on flashes = longer druation of flash ??

test the P45 and 5d at SAME ISO

Else

the 'PW problem'

(you might be able to solve this by using the PW to fire a small strobe on low power which would then trigger all the bright flashes at the same time)

Reprt back please

S
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Snook

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Stopping motion with studio strobes and MFDB
« Reply #2 on: December 01, 2007, 07:35:42 pm »

Quote
I shoot people jumping and doing motion stuff from time to time, and even if I use my H2's top sync speed of 1/800, i seem to get a slight blur every time, the blur is the same, no matter what sync speed i use (unless it starts dipping below 1/80 or so, but I never go there unless i need it for effect.)

I don't get this on my canon 5D to the same degree, and have no explanation for it. I have speculated on these three possibilities:

1. The P45+ (previously H3D) has a larger resolution, and this somehow captures the blur more "clearly". I don't see why it should be like this, but a dealer brought this as an explanation.

2. I use one pack with pocketwizards, and let the other ones sync by the first packs flash burst. Effectively this would mean one pack flashes first, and all the others at the same time, but with a small delay behind the first. Could this be the culprit (and do i then need to buy a lot of pocketwizard recievers?)

3. My Profotos just don't have a short enough flash burst at medium power? (I use an Acute2 1200, a Pro-B and AcuteB600R, as well as some compacts if I need it.)

Anyone have the bullet proof recipie for motion stopping studio strobe use with a P45+ on a H2.

-axel
[a href=\"index.php?act=findpost&pid=157567\"][{POST_SNAPBACK}][/a]
I can Tell you have posted in many forums asking the same question because I always got it but with the 1DsMII and 1Ds.
The Acutes 1200 actually have pretty bad Short flash duration and are the worst of the line almost.
I have 3 Acute 1200R packs and several Compact Mono s as well and the 600BR.
You must use the pack with like one head on Minimum power.
Forget the Compact they STINK for Freezing also.
Some Bowens like the 1500 mono and the 750's are actually pretty darn good.
I got in many deep discussions with people trying to tell me I need to Black out the studio etc... That was very obvious to me since I have been shooting for 18 years.
It has a lot to do with Flash duration.
I know I guy that shoots with the P45 and he told me he would never use it for an action stuff or Kinds that run a round a lot..:+}
But I am sure it is the lights most likely.
Check out the Flash Durations on the Info for the Lights you have or want.
The Acute 600BR actually has a short flash duration and I use that a lot or my Bowens over the Acutes.
Hope that may help you a little
Snook
« Last Edit: December 01, 2007, 07:37:36 pm by Snook »
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mattlap2

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Stopping motion with studio strobes and MFDB
« Reply #3 on: December 01, 2007, 08:00:34 pm »

Quote
I shoot people jumping and doing motion stuff from time to time, and even if I use my H2's top sync speed of 1/800, i seem to get a slight blur every time, the blur is the same, no matter what sync speed i use (unless it starts dipping below 1/80 or so, but I never go there unless i need it for effect.)

I don't get this on my canon 5D to the same degree, and have no explanation for it. I have speculated on these three possibilities:

1. The P45+ (previously H3D) has a larger resolution, and this somehow captures the blur more "clearly". I don't see why it should be like this, but a dealer brought this as an explanation.

2. I use one pack with pocketwizards, and let the other ones sync by the first packs flash burst. Effectively this would mean one pack flashes first, and all the others at the same time, but with a small delay behind the first. Could this be the culprit (and do i then need to buy a lot of pocketwizard recievers?)

3. My Profotos just don't have a short enough flash burst at medium power? (I use an Acute2 1200, a Pro-B and AcuteB600R, as well as some compacts if I need it.)

Anyone have the bullet proof recipie for motion stopping studio strobe use with a P45+ on a H2.

-axel
[a href=\"index.php?act=findpost&pid=157567\"][{POST_SNAPBACK}][/a]

Godfrey,

My guess is that it is the flash duration of the Profoto packs.  Neither the Acute 2 1200 or the Pro600B have fast flash durations.    At full power the Acute 1200 will give you a flash duration of 1/560th at 1200ws with one Acute head.    You can speed this up by going to a Twin head which will speed it up to 1/1000th.   Also dialing down the power will give you a quicker flash duration.

If you have access to some Pro 7 units you can get a much fast flash duration.  A Pro 7A 1200 pack will give you a starting flash duration of 1/2200th of a second at full power.

To put this in perspective most sports shooters shooting arena work will use a minimum of 1/2700th of a second and I believe the NBA requires 1/3000th of a second.

Other units that can get you a very fast flash duration are Broncolor Grafit, Elinchrom Micro S packs, Speedotron 2403 pack with a 105 head (2 cable or 4 cable).   Elinchrom also used to make some very fast flash duration monolites.  They were a special series and I am not sure they are still available.

Matt
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Graham Mitchell

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« Reply #4 on: December 01, 2007, 08:54:01 pm »

The extra resolution will mean more blur, but the greatest factor will be flash duration. You already have received some good advice here.

I'd recommend using Pro7 instead. The flash duration is as fast as 1/12,000. This is why I went for the Pro series over the Acute series.

I couldn't find a faster studio flash than the Profoto Pro series when I looked around. I don't have problems with blurred jumps.
« Last Edit: December 03, 2007, 04:25:15 am by foto-z »
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DavidP

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« Reply #5 on: December 01, 2007, 09:01:15 pm »

If you split the flash output into multiple heads, or use a bi tube head. That should shorten the flash duration as well. I used to use Normans and I know the full power duration at 2000 watt seconds was only rated at 240th second on those old Klunker 2000D packs. Using a lower power setting should shorten flash duration as well.
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EricWHiss

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Stopping motion with studio strobes and MFDB
« Reply #6 on: December 01, 2007, 09:46:35 pm »

Just to confirm those that posted before me, I can tell you the acutes have a slow flash duration.  

I've got the profoto D4 1200 w/s pack.  Its supposed to be fast but I measured the flash duration with my Mumford Time machine. At max power it went slower than 1/125 s. ( I think the Time machine reports .1T - so most of the flash, not just the .5T you see in spec sheets).   I'll be your acutes are giving you a flash duration at max power of something like 1/200s or slower  if they are similar to my D4.  

 You could confirm this shooting a series of images of some object where you hold the aperture constant and vary the shutter speed from like 1/200 to 1/800.  If you find your histogram going down as you increase shutter speed then definitely the flash is slower than the shutter as if it were faster the exposure would be the same throughout the different speeds.
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AndreNapier

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« Reply #7 on: December 01, 2007, 10:29:52 pm »

Another thing to consider is your ISO and aperture. Assuming you shot wide open at 2.0 or 2.8 at ISO 200 and use full power of your 300W modeling lights they will have huge influence on your blur at almost any shutter speed. I was reading in the other post about Mamiya synch at 1/60 or 1/90 and a comment of this not being a problem in a studio. The only way I can see it not influencing the color temperature and blur would be in a completely dark studio. I shoot hot lights and HMI's all the time and know that three 300W modeling lights from portrait distance are more that adequate to capture perfect lighting. Even if your strobe burn at 1/2000 sec the shutter stays open for remaining of dialed shutter time and the sensor keeps on recording all motion luminated by your modeling lights.
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AndreNapier

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« Reply #8 on: December 01, 2007, 10:41:12 pm »

I also noticed that DSLR's are much more sensitive to studio lights. When my A75S calls for 4.0 at set lights , Canon will be correctly exposed at almost 8.0. Matter of fact all my pro Elinchrom lights
are too strong for Canon wide open and I would be forced to use f11 or higher. This would have huge influence on the ratio of hot to strobe intensity and also on any recorded blur.
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mcfoto

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« Reply #9 on: December 01, 2007, 10:42:58 pm »

Hi
For the best flash duration I use Broncolor Grafit @ 1/3200 duration. I rent these packs for the jobs that require movement. I use the AFDII with a Aptus 22 back or really it doesn't matter what you shoot on. I have not used the Prfoto pro 7 packs & I have heard they are good too. The advantage of the Broncolor Grafit packs is that you can dial in the flash duration. My Acute 12 pack is useless for movement in the studio.
denis
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mtomalty

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Stopping motion with studio strobes and MFDB
« Reply #10 on: December 01, 2007, 10:44:34 pm »

You may want to contact a formar poster here,Peter Schafrick.
He has become know for his very compelling 'splash' images for advertising.

some examples of his work can be found in the 'liquid' gallery at www.peterschafrick.com

He has a lot of experience and has posted extensively on the flexframe forum recently
about flash duration,etc.

The short answer is that the Broncolor line has among the shortest flash durations

Mark
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Rick_Allen

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« Reply #11 on: December 02, 2007, 02:46:53 am »

I digital/lighting tech for a guy that shoots lot of beverage campaigns and he always shoots with Bron Grafits. I found that you can never use the CELL to slave the units mostly we use the Bron IRX trigger or hardwire and all packs need to be either at the same power setting or as you can dial in duration with the grafits at the same speed.
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paul_jones

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« Reply #12 on: December 02, 2007, 02:49:21 am »

all the flash units have faster flash duration at lower power. but if you need more power, a good idea is to use two packs on the lowest setting you can live with.

the pro7s are quite fast, but the broncolor grafit has a higher speed sync by some how cutting off the power before the flash duration is finished (some bron expert may explain better than me), but it comes at a cost of very low output.
when i have wanted quicker duration and more power, i have put two or more heads mounted in a softbox- its a cheaper way to do it than twin head.

years ago when i had elinchrom, i use to hire elinchom 250R ("R" was for a rapid version of the standard el250 mono), and they where real fast. ive also heard the new bowens packs are pretty fast.

paul
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eronald

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« Reply #13 on: December 02, 2007, 04:25:17 am »

AFAIK with a simple flash design, more powerful flash settings are *shorter*. I know this sounds weird, but that's what the original designer of the Elinchrom units told me.


Edmund
« Last Edit: December 02, 2007, 04:28:10 am by eronald »
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godtfred

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« Reply #14 on: December 02, 2007, 05:40:50 am »

Thanks everyone for excellent feedback. I guess I'm going to rent me a bron kit or a Pro 7 kit when I need action stopping power. I was looking at buying a D4 2400R in the near future, but now I may think again...

To the poster who wrote on the canons needing less light for the same f-stop, this is my experience as well. It seems to me my 5D has around ISO 150-180, when set to 100.

-axel
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Frank Doorhof

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« Reply #15 on: December 02, 2007, 05:47:12 am »

Hi,
I also do ALOT of motion in the studio.

The flashduration is key.
I use an Elinchrom A head on a Ranger for the REAL FREEZING, on full power it gives me 1/5400 which is enough to freeze a jump.

If I want a slight blur in the feet but a perfect sharp face I will use the RX units, they will give you 1/3000 app.

On FULL power you will get the fastest flashduration, on low power the longest.

With the small on camera systems this is the opposite way.
But they are VERY on the lowest settings.

So in short it's all in the flashduration.

The only thing that took me a while to get used to was the slower lag in the Mamiya opposite to the Canons I used.
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Graham Mitchell

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« Reply #16 on: December 02, 2007, 08:06:08 am »

Quote
On FULL power you will get the fastest flashduration, on low power the longest.
[a href=\"index.php?act=findpost&pid=157628\"][{POST_SNAPBACK}][/a]

It is definitely the other way round on the Profoto Pro series. Not sure about others.
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Snook

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Stopping motion with studio strobes and MFDB
« Reply #17 on: December 02, 2007, 08:27:45 am »

Quote
It is definitely the other way round on the Profoto Pro series. Not sure about others.
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Frank I cannot say much about Elinchroms , But they must be the ONLY ones that work that way.
you MUST have the Packs on LOWEST setting to get the SHORTEST flash duration on MOST ANY PACKS... Period!
So what your saying is just the OPPOSITE of the norm!
But hey.. Maybe Elinchrom did something special in their packs.
But it is opposite on:
Profoto
Hensel
Bowens
Speedotron
Dynalites
Broncolor
Norman.
Snook
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jpop

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« Reply #18 on: December 02, 2007, 09:07:39 am »

Capacitors work like a 55 gallon drum filled with water.  When I poke a hole in the bottom of the drum the water at first comes out fast and as it gets closer to the bottom it slows down.  Most packs when running at half power will only fill up a capacitor half way which gives you the slower part of the discharge.  Bank switching of capacitors when dialing a pack down, and not filling all the capacitors will make for quicker flash duration, but will place some capacitors into overuse.  On some packs there is circuitry designed to stop the flow of currency before the capacitor is fully discharged, hence allowing only the fastest part of the discharge to the heads.  

There was also mention of bi-tube heads and how they effect flash duration.  Using the 55 gallon drum filled with water example again, if I fill it with water and poke two holes in the bottom, the water evacuates twice as fast, hence shorter flash duration.  The same can often be achieved with multiple heads, as long as the pack doesn't have separate banks for each lamp head outlet.  In part this is why Speedotron hangs from the rafters of the majority of Pro Sports Arenas in the States, quad-tube head, big power, decent recharge time despite having the elegance of an anvil.

For quick flash duration work it's also important not to rely on white light slaves.  To date I haven't seen any packs or slaves that don't produce a slight delay, although quite possibly splitting hairs for most subjects.  Best to hardwire the packs or use multiple receivers with pocket wizards or any other type of wireless transmitters.  

I hope that someone can make use of this information while also understanding that it might not be absolute with the type of gear they are using.  I did my testing using a flash duration meter and a variety of packs at my disposal, Broncolor, Speedo and Profoto being the primary.  There are also quick burn flash tubes available from some of the manufacturers or third parties that will decrease flash duration but just as quickly decrease the life of a flash tube.  

I also hope that there is some understanding and compassion for those of us who don't take pictures for a living but simply try to help those who do take better ones and provide the answers when they have a demanding or challenging set of circumstances.
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ctz

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« Reply #19 on: December 02, 2007, 02:11:07 pm »

Quote from: Snook,Dec 2 2007, 03:27 PM
Frank I cannot say much about Elinchroms , But they must be the ONLY ones that work that way.
you MUST have the Packs on LOWEST setting to get the SHORTEST flash duration on MOST ANY PACKS... Period!
So what your saying is just the OPPOSITE of the norm!



I sometimes use fast (1/6600) Elinchroms and they are indeed fastest at the full power (indeed, full power means 250Ws for the monoblocs called "250R").
At least that's in specifications and the results in the real world seems to confirm that.
Also the A3000N heads give a pretty fast speed (1/2000 aprox) on the AS generators.
And also Hensel has a breed of pack/heads combination (I can't recall the names) capable of 1/7500, also at full power (1500Ws with all the 3 heads at a time, meaning 500ws per head).

They are the OPPOSITE of the norm because all use a different "scheme" of... well, downshifting, being designed mainly for short flash duration at full power.
The drawback is that all of these fast strobes are also shorter on life expectancy...

HTH
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