Shortest flash duration

Hello,

 

I have a job to organise taking place next week. We intend to portrait people

performing fast, jerked movements. The shoot will take place in a studio, will

be lit artificially and will be shot on 120 film.

 

In order to capture the fast jerked movements of our models we need to use a

combination of fast shutter speed and short flash duration. Firstly, we plan to

use a Hassleblad V system camera because, as far as I am aware, the leaf shutter

on these cameras will sync with flash even up to 500th second exposure times.

Can anybody confirm this?

 

Secondly, we need to find a flash unit which will give us a very short flash

duration in order to capture this movement. It has been recommended that we use

the Broncolor A4 Grafit flash unit as this has a very short flash duration when

the power is turned down lower. Can anyone agree/disagree or suggest other options?

 

Much appreciated,

Thom

Depending on your setup and requirements, I'm not sure about other manufacturers, but many Canon speedlights can "sync" at very high shutter speeds. I was taking photographs with speedlights at 1/2000 at the weekend.

 

They can also be used to very creative effect when off camera, and combined with other speedlights and reflectors.

 

Speedlights used on LOW power will also produce a VERY short duration flash, so you can have your shutter open as long as you want, if your studio is dark until the flash goes off.

 

Of course, you may well hit a stumbling block with the Blad and using 120 - but if you're ONLY using this to get the fast sync, be aware that the above option is available (and widely used).

If the room is dark enough then the shutter speed is not an issue. Just set it at the highest sync speed and the flash will freeze the action. You may find this link interesting: <http://www.daveblackphotography.com/workshop/arena-lighting.htm>

You don't need fast shutter speed. Set the shutter at x-sync (even if it's 1/30s as is the case on some cameras) and keep the ambient lighting low. Most flash units will have a duration of 1/500s or less (the lower power settings will have a shorter duration) which has the same net effect as a fast shutter speed. Pretty much any mainstream flash units will work.

That's the "strobe" effect. However, this only happens at the lower power level the flash supports. People use this technique (and flashes like the Vivitar 283 which can be hardwired for shortest flash duration) to take pictures of water drops.

 

In real life, it probably won't matter as much...you should easily get 1/5000 even at full power with flashes. Just focus on getting the fastest x-sync speed you can find (ignore High Speed Sync mode which is a misnomer for slow sync :-)...

it's all about flsh duration and eliminaion of any ambient light. All pro level flash equipment

should give you what you're looking for if you dial the power all the way down. So get the

lights in close, use regular or shiny reflectors etc. In my experience (stopping a jumprope in

midair) Pofoto Pro-6-7 does the best job. bron makes it a big sales point but if you use their

flashduration function you only lower the power settings available. All of the above results in

the the same short flash. But if you have only other equipment available, check their tech

specs, the one thing i know that doesn't work is Profoto Acute

best

MS

First of all, if you want to freeze motion pay attention to the t0.1 flash duration not the t0.5 flash duration. t0.1 is a better standard for actually freezing motion. t/0.5 times are usually quoted and are shorter than t/0.1 durations but do not take into account the full length of time the flash tube is glowing so a t0.5 of 1/600 may cause a trailing blur whereas a t/0.1 duration of 1/400th will not.

 

Shutter speed is not generally an issue unless you have a flash system with a t0.1 duration of 1/250th or longer. Along with the Broncolor system you mentioned the Profoto 7 Freeze system would be a good choice as is a Speedotron with a quad-tube head. With any flash system 1/125th is a choice. If you are going with the Hasselblad or another film camera, it is always best to shoot Polaroid tests.

 

The Broncolor Grafit is good , but really any pack and head system that has a bi- or quad-tube head option will work as long as you can divide the total power output equally amongst the 2 or four flash tubes.

 

If you need to take the photos in rapid sequence consider a quad-tube head from Speedotaon and 4 Speedotron packs. Combine this with a Pocketwizard MultiMAX sytem ((you'll need 5 transceivers , one on the camera as transmitter, and then one as a receiver on each pack, each set to a different subchannel of channels 17-32). the transmitters is then set to rotate through the four subchannels giving the individual packs time to recycle.

 

 

 

If you are in the Northesat USA You should really talk to the people at

 

http://www.flashclinic.com

 

about rentals and how to set the system up.

 

In the Southeast:

 

http://www.ppratlanta.com

 

In the Southwest, http://www.lighttec.com

 

In the midwest: http://www.helixphoto.com and http://www.calumetphoto.com (the latter is good for just about everywhere in the USA including NYC).

 

In southern California, there are a number of places I've dealt with: Calumet Photo, Irena's PRS, and Samy's.

 

How large is the subject you are lighting? If it is smaller than breadbox Speedlights from Nikon or Canon in manual mode may be the better tools.

 

Ambient light concerns: low ambient light levels are really not necessary unless you have extremely bright ambient light like mid day sunshine or large f/stops like f/5.6 or larger at ISO f/16 @ 1/250th is going to put mid day sun at 1 stop under so if you are in a studio, and using a shutter speed of 1/60th or shorter I just would not worry too much about the ambient light levels. Most of the blur people see in moving subjects lit by pack and head lights or mono-lights is caused by a long t0.1 flash durations.

 

http://www.broncolor.com

 

http://www.speedotron.com

 

http://www.pocketwizard.com

 

http://www.profoto.com

Thanks everyone, that's all rally helpful and too much information to respond to individually! Thank you, a great help.

Thom

You'r e welcoms.

 

Clarification. My last paragraph should have read:

 

"Low ambient light levels are really not necessary unless you have extremely bright ambient light like mid day sunshine or large f/stops like f/5.6 or larger. At ISO 100, f/16 @ 1/250th is going to put mid day sun at 1 stop under the flash exposure so if you are in a studio, and using a shutter speed of 1/60th or shorter I just would not worry too much about the ambient light levels. Most of the blur people see in moving subjects lit by high powered electronic flash is caused by a long t0.1 flash durations."

A Nikon SB-800 has a duration of about 1/80,000 second at the lowest power setting. Full power has a duration of about 1/1500 second. If you need something faster or more powerful (e.g., your subjects are from the planet Krypton), you need low-impedance circuitry, including oil-filled capacitors instead of electrolytics, high voltage (1500+ instead of 325 or so), a large bank balance and an up-to-date will.

<br>Adding to Edward's comment above, for more power at high speed such as 1/80,000, you can use multiple SB-800 units. Search the web, there are mounting brackets that allow you to mount multiple flashes.

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