High speed with flash

Discussion in 'Photography Beginners' Forum' started by fokker, Sep 20, 2009.

  1. fokker

    fokker No longer a newbie, moving up!

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    So I have a question regarding using fast shutter speed (maybe 1/500-1/800 would be nice) to stop motion on a prticular subject using a strobe (540EZ with some cheap wireless trigger). I can't seem to go any faster than 1/200 - is this just the limit of my gear (400d and 450EZ)? If so, which is the limiting factor? If not, how do I go faster?

    Thanks!
     
  2. Alpha

    Alpha Troll Extraordinaire

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    The limiting factor in this case is your shutter speed. Any faster and the flash can't stay properly synchronized with the shutter. This, of course, is a limitation on your camera. For cameras that can sync at high speeds, flash duration can become a limiting factor.

    What are you trying to shoot?
     
  3. Plato

    Plato TPF Noob!

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    It's the limit of the mph speed of the shutter curtains. With your camera, anything shorter than 1/200 means that the closing curtain starts moving before the opening curtain reaches the bottom. The result is that there is no instant when the entire frame is open. You have a moving slit. Since electronic flash is effectively instantaneous, you would illuminate only the slit. Modern cameras protect you by not allowing flash speeds higher than the max that can be handled.

    FP flash is a solution (if your camera AND flash can handle it) but it has disadvantages. Effectively an electronic simulation of the old long-burning FP bulbs, the flash fires continuously. It begins firing before the first curtain moves and is still firing when the second curtain closes the shutter. Although technically not the correct semantics, the flash intensity drops significantly.
     
  4. gryphonslair99

    gryphonslair99 Been spending a lot of time on here!

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    Disregard. Can't be done with the flash unit you have. I you are willing to get something like a 430 or 580 you could use HSS.
     
    Last edited: Sep 20, 2009
  5. musicaleCA

    musicaleCA TPF Noob!

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    The limiting factor is your camera body, specifically the speed of the shutter. That is, how quickly the shutter curtains can race from one end of the focal plane to the other; the faster they can move, the higher sync speed you can have, because the longer they can stay completely open (both curtains open and sensor fully exposed) for shorter and shorter amounts of time. The flash needs to fire somewhere in that instant where the two curtains are both open, otherwise the light from the flash will likely be blocked by part of the rear curtain as it closes. This is why the camera body stops you from setting a shutter speed higher than 1/200. On older Nikon bodies like the D60 (this is hearsay, and I might be confused about exactly which models can do this little feat), the sync speed can run as high as 1/500, because the exposure is stopped electronically. Of course, that in turn means you're using a CCD sensor which has it's own problems.

    Now, to get around this, some flashes support high-speed sync, which actually just pulses the flash very quickly during the exposure to mimic continuous light, allowing you to use the flash at speeds as high as 1/4000. But, the trade-off is power, and the guide number falls off dramatically as you increase shutter speed beyond the sync speed of the camera.
     
  6. manaheim

    manaheim Jedi Bunnywabbit Staff Member Supporting Member

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    hahhahah...

    See, this is why I love TPF. I got threatened and told I was going to be banned... but this guy gets a pass.

    Awesome forum. :thumbup:
     
  7. Jaszek

    Jaszek No longer a newbie, moving up!

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    Nice lol.
     
  8. thenikonguy

    thenikonguy TPF Noob!

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    you back>??
     
  9. Jaszek

    Jaszek No longer a newbie, moving up!

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    Now this forum is going like it used to be, great members that give good info and annoying ones that many people hate :D
     
  10. KmH

    KmH Helping photographers learn to fish Supporting Member

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    When using flash, the duration of the flash of light is much shorter (like 1/1000 sec at full power) than the shutter speed at the camera's max regular flash sync speed (about 1/200, depending on the camera).

    At less than full power the flash duration can be as short as 1/40,000 of a second. (1/128 power)

    The other consideration is whether the flash triggers once the first curtain is open or as the second curtain begins to close.

    As it turns out, when you are using flash the shutter speed controls the exposure of the background and the aperture controls the exposure of the subject and flash duration (w/second curtain sync mode) stops motion.
     
  11. fokker

    fokker No longer a newbie, moving up!

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    plato - manaheim etc. can you please throw faeces at each other somewhere that I'm not trying to learn. Thanks

    Others - thanks for the useful information. I also have a 380EX, will that be better?

    Alternately, from what I gather by your explantions, I would be better off freezing the motion by using a 1/200 shutter at high flash power, but cutting down on ambient light (I was also using a fairly bright spotlight to light the other side of the subject) and using the aperture to control the subject brightness? Does this sound more reasonable?
     
  12. Village Idiot

    Village Idiot No longer a newbie, moving up!

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    WTF are you trying to do? Stop being a waffle hat and respect your elders and people that are smarter than you.

    I could sit here and explain how a flash works, but there's books for that. If you explain what little picture you're trying to take and you're nice about it, I may be feeling generous enough to tell you where to put your settings for when you're ready to press th picture taking button.

    Then go buy a book that explains how flashes work. That or at least read a website.
     

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