A&P quick question about strobing.

Discussion in 'Lifestyle' started by ballz, Nov 26, 2007.

  1. ballz

    ballz Two of 'em OT Supporter

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    I don't understand all of this fully yet, but did do some googling without any real luck.

    why do speedlights have a high speed sync mode? what is actually happening when its turned on? what would be bad about leaving it on always?

    also, can someone explain ratios in lamens terms? or is there a site with good illustrations?

    thanks for your help.
     
  2. kristin

    kristin my dog > *

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    The high sync mode allows you to sync at a higher speed.. You turn it on, and instead of being able to only go up to 1/200th (or whatever your camera's sync speed is) you can go higher. I can go all the way up to 1/4000th if it's attached to the camera :dunno: But with off camera, it doesn't seem to work. I've seen a few posts on strobist about "hacking" the off camera stuff to make it work, but I haven't tried it.
     
  3. Derrict

    Derrict No, I am not Amish OT Supporter

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    in terms of both film and digital, you have to understand the mechanical nature of an SLR. without going into technical details (you can always google it), a too fast of a sync speed will result in an image that isn't fully exposed. this is a moot point with modern cameras that use an electronic shutter, which is much faster than the mechanical 'curtains' on the older film bodies.

    the only reason why modern cameras limit sync speed is for hot shoe flash efficiency (battery recycle, battery life, etc).
     
  4. mobbarley

    mobbarley Active Member

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    at high speeds the shutter cant open completely so it acts as a slit traveling over the film/sensor. To stop only a small part of the image being exposed by the flash (it has a VERY short duration), in HS mode the flash actually fires many times in succession and due to this output power is greatly reduced.

    so HS mode will compromise your output and thus your flash distance, however it should only do this if your camera approaches xsync speed. also I think that if you allow your camera to meter while the flash is in HS it may choose a faster shutter speed which may not be desirable. So no, dont leave your flash in HS, or if you do be wary of shutter speeds. :dunno:
     
  5. ballz

    ballz Two of 'em OT Supporter

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    so if standard can go as fast 1/200(on my camera), how does the flash bulb react differently at 1/250 when switched to high speed? does the bulb fire quicker or sooner than it would @ 1/200? and does the bulb fire even more sooner @ 1/1000 and so on?
     
  6. mojito

    mojito New Member

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    its actually several short bursts, so you lose a lot of power in doing it, so its fill only really.
     
  7. mobbarley

    mobbarley Active Member

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    did you even read my post :squint:
     
  8. Derrict

    Derrict No, I am not Amish OT Supporter

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    :mamoru:
     
  9. camptrol

    camptrol .

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    http://www.rpphoto.com/howto/view.asp?articleID=1026

    How it works

    Recall that in "standard" flash mode, the flash output is a very brief pulse, usually much shorter than the shutter speed. As flash engineers worked on ways to produce ever-faster stroboscope flash modes (many pulses per second for stop motion sequences or disco dancing), they realized they could pulse the flash thousands of times per second to produce an essentially continuous beam of light (for brief periods).
    So in high speed sync mode, the flash fires continuously, many thousands of times per second. All these pulses of light essentially merge together into one long "pulse" that stays on the entire time the shutter is open. This is a lot of work for the flash to do; but it only has to do it for very short periods of time (i.e., less than the standard sync speed, such as 1/200 sec or less).
    So in high speed sync mode, the flash stays "on" for the entire time that the shutter is traveling across the frame. There's no longer a problem with parts of the frame blacking out behind the shutter curtains as they sweep across the frame. Now you can use fill flash at shutter speeds of 1/8,000 second!




    Cliffs: Mojito is right.
     
  10. camptrol

    camptrol .

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    Ratios? What are you referring to?
     
  11. mobbarley

    mobbarley Active Member

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    fuck mojito :nono:
     
  12. mojito

    mojito New Member

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    :wtc:

    unless you're kristen bell then that would be :naughty:
     
  13. mobbarley

    mobbarley Active Member

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    if I was kristen bell i'd still be tryn to score hot chicks :naughty:
     
  14. mojito

    mojito New Member

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    :bowdown:


    [​IMG]
     
  15. Trlstyle

    Trlstyle New Member

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    Are you talking about ratios on strobe packs...stopping down a portable system? what?
     
  16. Derrict

    Derrict No, I am not Amish OT Supporter

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    scottwax needs to polish and detail that paint :hsugh:
     
  17. brasheye

    brasheye Rotary Crew

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    Get a camera with electronic shutter and sync at speeds so quick you will be overpowering the sun like zzzzzzuuuuess!
     
  18. mobbarley

    mobbarley Active Member

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    ratio |ˈrā sh ō; ˈrā sh ēˌō|
    noun ( pl. -tios)
    the quantitative relation between two amounts showing the number of times one value contains or is contained within the other : the ratio of men's jobs to women's is 8 to 1.
    • the relative value of silver and gold in a bimetallic system of currency.
    ORIGIN mid 17th cent.: from Latin, literally ‘reckoning,’ from rat- ‘reckoned,’ from the verb reri.

    :fawk:
     

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