Flash duration

After reading all the old searches I'm still confussed. I'm looking for a pack and

head system that I can use in an action setting, say martial arts for example. I'll be

using a Nikon D2x and want to freeze motion with no motion blur. After reading

Ellis's and Brooke's definitions my question are:

1. Am I correct in assuming that I want a fast(short time) duration?

In this case shorter is better?<p/>

2. If the camera can sync above 1/500's in the FP mode as it does with

speedlights, can I use the combination of fast shutter/fast flash duration to stop

action? Or am I restricted to the x-250? This is where the confussion comes in, I

understand the relationship with a speedlight, aperature and shutter speed, what I

don't understand is all the posts about shutter speed not affecting anything but

ambient. As stated above if I have my exposure figured out to say f/8 @ 1,000 in

a sunfilled room and then we make the room dark and we add the light system,

won't I need a flash duration at least that fast to freeze the same action?<p/>

3. I see in many explainations where people are trying to open the aperature or

slow the shutter to match whatever light they have,here I would like to match the

light, am I on the right track?<p/>

4. I don't want to stop a bullet, or make another sun, or light the whole east coast,

but I would like to start with something that would do the above and be able to add

on to.I understand you get what you pay for but does this animal exist with out

spending $5,000?<p/>

Thanks in advance for saving me money and time.

Jim,

 

Yes you want the shortest flash duration you can get.

 

Shutter speed has nothing to do with flash duration. If you have a lot of ambient light in your room then a faster synch/ shutter speed is helpful but only in limiting ambient light. And 1/1000th of a second isn't nearly fast enough to stop the kind of motion you're wanting to stop.

 

Unfortunately there are few studio strobe systems with short enough flash durations. Some Balcar packs do but they're extremely expensive for that one feature.

 

Smaller, off-camera flashes usually do have flash durations shorter than 1/2000 of a second but they are limited in output. Still, you could gang several small camera flashes together, behind a large silk so they act as a single source and achieve a reasonable f-astop at a higher ISO and a very short flash duration.

Well you can forget FP mode with anything other than Nikon speed lights. That mode involves pulsing the flash a number of times to give illumination as the shutter gap travels across the image sensor.

 

Yes you want a short/fast flash to freeze action, which means a high output so you can close down the aperture to eliminate natural light casing blur at the x-sync speed of the shutter.

 

Shutter speeds below the x-sync value affect ambient light, as you can't use a shutter speed above x-sync speed with an external non dedicated flash.

 

For example, if the room illumination gives you 1/250 at f11, and the flash calculator is f11 at the same distance, you will have motion blur.

 

With your example of natural light at f/8@1/1000 giving you no motion blur, yes you will need a flash with a duration no longer than 1/1000 sec. Now this will exclude a number of studio flashes that have flash durations as slow as 1/250 sec.

 

Probably what you are looking for is one of the potato masher style of flashes that are thyristor controlled to limit light output. These units can produce flash durations as short as 1/10,000 sec at close distances.

 

A Metx 45 or 76 series ought to do the job, but be prepared for a whole bunch of sticker shock!

This powerpack and head is popular with sports location shooters

http://www.bhphotovideo.com/c/product/532562-REG/Elinchrom_EL_10287_Ranger_RX_Speed_AS.html

 

The Freelite A head can freeze action at 1/5120 sec and that's why a lot of sports guys like it.

 

Personally, I don't shoot sports. My lights have about 1/1700 sec flash duration and work fine for fashion/portraiture type stuff.

1. Am I correct in assuming that I want a fast(short time) duration? In this case shorter is better?<P>

 

<B>If you are photographing objects or live subjects that are moving , the answer is yes.</B><P>

 

2. If the camera can sync above 1/500's in the FP mode as it does with speedlights, can I use the combination of fast shutter/fast flash duration to stop action?<P><B>Not with lights that are not part of your camera's system. What the Nikon D3 and SB-800 (just an example) are doing in FP mode is that the camera and flash synchronize a stream of low power flashes with the narrow open gap as the shutter curtains move across the gate i nthe camera.</B><P>

 

Or am I restricted to the x-250?<P><B> With strobes from outsiode the system , that is your limit. However there are some older D-SLRs (I think the Nikon D70 and D1x seriesdo this) of these where yo u actually can sync at a shorter r shutter speed with flash equipment. The problem with using studio strobes this way is that, dependiing on the pack and head or monolight system and the power level it is set to , your shutter speed even at 1/250th may be shorter than the flash duration so you mightget some unexpected under exposure. </B><P>

 

This is where the confusion comes in, I understand the relationship with a speedlight, aperature and shutter speed, what I don't understand is all the posts about shutter speed not affecting anything but ambient. As stated above if I have my exposure figured out to say f/8 @ 1,000 in a sunfilled room and then we make the room dark and we add the light system, won't I need a flash duration at least that fast to freeze the same action?<P><B>Yes you will.</B><P>

 

3. I see in many explainations where people are trying to open the aperature or slow the shutter to match whatever light they have,here I would like to match the light, am I on the right track?<P><B>If I am reading you right , you are.</B><P>

 

4. I don't want to stop a bullet, or make another sun, or light the whole east coast, but I would like to start with something that would do the above and be able to add on to.I understand you get what you pay for but does this animal exist with out spending $5,000?<P><B> One trick with any good mid-level system (Profoto Acute 2, Dyna-Lite M series, Alien Bees Zeus, Speedotron Blackline, Hensel Tria, etc.) is to use a bi-tube head. This is a head that as the name describes, is essentially two heads in one and each flash tube connects via its own cable to either two channels on one pack or to two seperate packs. Speedotron doesn't make b-tube however: they make a quad-tube head , essentially 4 heads in one.<P>

 

if you are looking for short flash duration and good solid gear (though not the prettiest system you'll find) at a comfortable price the paul C Buff Zeus system is really good in this regard. settign the 2500 watt-second version of the pack to isolate the A/B channels and just using the B channel with the slidign variator set to full power ( 625 w-s max on the isolated B channel) the t0.1 flash duration is 1/670th second. This is according to my independent measurements with a Broncolor FCM meter not the manufacturer's specs. I haven't tried the Zeus with their bi-tube head but suspect that at 2500 w-s with the bi-tube head the t0.1 flash duration will be in the 1/500 -1/600th second range. <P>

 

 

By the way, Elinchrom's specs say that with two A heads on a Ranger Rx Speed the t/0.5 flash duration is 1/4310th second . Since the t0.1 flash duration is 3 times longer than the t0.5 duration is more like 1/1435th second than Mr. Trance's claim of 1/5120 and a single A head o n that pack will have a t0.1 of 1/766th second. Even disregarding f Mr. Trance's hyperbolic exaggeration that is still impressive. Elinchrom makes solid gear as well. <P></B>

Elinchrom's website says 1/5120 and B&H says 1/4120....so there's probably a "typo" somewhere

Hey C.T.,

 

my flash duration specs came from http://www.elinchrom.com/products/specifications/specifications.pdf

A output: 1/2300 s / 1/4310 s

B output: 1/5120 s

 

1/5120 s is only available when using a single freelite A head on the b output of the RX speed AS pack.

 

Cool...That's good to know in case I ever have to rent an AS Pack for a shoot. Right now I've just got a regular RX + S heads.

That is cool to know . We've got a great rental house here in Atlanta and I'll check with

them to see if they have the RXspeed in stock.

You are correct that a short flash duration is critical.

 

Broncolor has pack/head lights with the kind of short duration you are after.

 

Bowens Quadx pack/head system also has the very short flash duration.

 

Those systems are quite expensive. Expect to invest as much as $10,000.00 in them for purchase. A rental for a shoot won't be cheap either.

 

 

You need to shoot with minimal ambient light if possible.

 

The exposure is created entirely by the flash output level and flash duration.

 

Bowens Quadx information

 

http://www.bowens.co.uk/catalog/product_info.php?products_id=248

 

 

Good Luck ...

Gentlemen, thanks for your help.