I was told that for shooting sports/motion in studio you want to shoot at 250 second ( I have the 5D) and you also want a power pack to be able to fire off at short durations.
What does that last part mean exactly. thanks!
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This is referring to the flash duration of the specific or chosen flash device. There are self contained flash units (Canon 580... / Nikon SB800...) etc and these are small camera mounted devices. They can also be used off camera with cord extensions and hand held with other accessories.
The other type of flash or strobe systems are power pack or monolight rigs. The power pack is the most conventional and has a case which contains a lot of electronics that flash heads plug into with a cord. These cords can be 20 or even 40 feet long. Most packs can have anywhere from 2 to six of these corded flash heads plugged in at any given moment. The third type which is somewhat newer in design then power packs is Monolights where the flash head itself contains the power modules and electronics necessary to flash.
With most of the types of flash systems mentioned above you are able to control not only the amount of power at the time of flash but also its duration, by shortening the duration and increasing the power you can output a lot of light in a short time period anywhere from hundreds to hundreds of thousands of a second. The shorter durations are achieved usually with higher end or specialized gear, especially if high power output is required.
I used to use a bunch of small Vivitar 283 model flashes which can do extremely short duration at low power for some of this kind of work. But if you are talking about freezing humans which can cover relatively large areas when moving fast you will probably want high output short duration power pack/monolight units chosen for this capability.
Good luck
__________________ Rick Unland
"Heaven goes by favor. If it went by merit, you would stay out and your dog would go in." - Mark Twain
White Balance so easy, even our 5 year old can do it.- Melissa Strickland
Last edited by Run; 09-10-2008 at 10:56 AM.
Reason: grammer:-)
you need a fast flash duration...ie dial the power down on the strobes. shutter speed doesnt matter just dont blow your sync speed, its best to shoot at highest though without blowing so ambient light wont affect it. strobe packs dialed down to lowest power or shoe mounted flashes dialed about 1-16th power or less should do it. experiment.
flash duration is the time the flash tube is lit up, the duration of the flash. its kindof your shutter speed in a way, since aperture is the only on camera exposure control that affects exposure assuming you dont blow the sync speed.
an understanding of flash duration is how i photograph water droplets, and ballistics with an air pistol or real fire arms and stop the action. the last taking a very specialized flash i didnt own. but everything else is possible with a moderate equipment set up consisting of vivitar flashes.
Thanks Guys,
The studio I'm going to rent for this motion project is supplying the power packs. Not sure which brand yet. But are you saying that if the pack can set at 800 watts or 400 watts or 200 etc, and you can trim lower, you want to have lowest setting? And why would this freeze action better? And then you would have less power correct? ie, would not be able to shoot at high f/stops. Hope I am understanding well
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Yes you understand correctly, the lower the wattage setting the shorter the duration of the actual flash. I would have to have a model number and do some research to tell you what duration times would be for each wattage setting on those particular packs. I use Norman Power Packs and a 2000ws unit can strobe durations from 1/250th @ 2000ws to 1/1200th of a second 400ws. It is not intended for high speed shots of the type you are contemplating. Although with heroic measures in modification (expensive) they could be made to do so.
To freeze an object in motion requires a flash duration short enough to not have the object move during that time period. The faster your object is moving in relation to the camera the shorter the flash duration has to be to stop or freeze the action without showing any motion blur Motion blur - Wikipedia, the free encyclopedia .
Smaller units of the hand held variety such as the Vivitar 283 can be manipulated to produce durations as short as 1/30,000th of a second. If you find out what power packs they have let me know and I am sure I or someone else can tell you how short a duration that pack is capable of delivering.
If you are interested in professional systems you can try High Speed Flash
Also there is a great thread about high speed flashes and who makes them and how they work at Olson High speed flash units for hummingbirds - Photo.net Nature Forum one of the people in the thread is a Professor from England I think that invented some of the greatest high speed equipment around.
Good Luck with your shoot
__________________ Rick Unland
"Heaven goes by favor. If it went by merit, you would stay out and your dog would go in." - Mark Twain
White Balance so easy, even our 5 year old can do it.- Melissa Strickland
Last edited by Run; 09-11-2008 at 01:49 AM.
Reason: added link
see if the studio has profoto 7A packs, they are amoung some of the shortest flash durations. stopping power is also dependent on subject contrast, lower contrast scenes need less but high contrast need fast durations.
i recall hearing from speedotron (speedo and norman are amoung the longest durations even at lowest power) that a photog used a light to shoot a dance event, the dancers were wearing dark clothes against a black background but wore metallic belt buckles. the dancers were stopped by the buckles blurred.
all flash durations are measured in "t" the standard is t=0.5 meaning that its measured from when the flash reaches 1/2 of its brightness and falls to 1/2 of its brightness. this is usually fine for normal situations, normal contrast, but for absolute ease, a t=0.1 is best, that is when the flash reaches 1/10th of its brightness and returns to it. it will be a much longer time but metallic objects will be lit from this light.
speedo and norman are specd at t=0.5 durations, but their t=0.1 times are insanely longer....like so long i wouldnt reccomend using them at any power.
i would probably request some bright lights, 1-2k tungsten lights and use a fast shutter speed and iso 400-800. forget flash. flash is good for close up due to lower brightness output from the faster duration flash.
the vivitar 283s will do anything you need....look into the pal flash from the cook corp or the EGG microflash for ballastics, they both have sub microsecond flash durations.
Speedotron and Norman packs are the most common strobes for permanent arena set ups, mainly for their ruggedness, power, and generally low cost compared to something like the Profoto units (which are great, as long as you're willing to mortgage your house to get some). I once saw Speedo packs the size of suite cases come out of a sports arena after being in the rafters for 20 years without an issue.
The trick to getting short flash durations is to use multible heads on the same circuit. If you have a 2000W pack, instead of running one light at 2000W/sec, run run 4 off the 800w/sec channel, and two off the 1200W/sec channel.
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