Wireless Flash/High Speed Sync

Discussion in 'Lighting Equipment' started by acurlee, Apr 25, 2007.

  1. A little background: I have a Canon 30D, a 580 EX speedlight, and a 24-70 2.8L.
    I am trying to photograph dogs at night in very low light. Due to the lighting
    I am looking for a wireless system, with a high sync speed. I have to shoot
    1/640 sec to stop the action. The pocketwizards and the quantum units have a
    cut off at 1/250. The Canon system doesn't have the distance that I need to
    keep the enviorment safe. I've tried the 580 at all kinds of settings and with
    a diffuser (lightsphere) and can get a balanced look, due to how dark the
    enviroment is ( have no control over this, it is rarely done in the day, or
    places with decent light at night). I can't afford the big strobe units and
    having extention cords to light work lights would be a hazard. I am looking
    for a kit with hotshoe flashes that I could use for this application as well as
    other (portait or candid) work. Can anyone recommend a wireless system as well
    as flash units that would be good in this type of situation?

    Thanks for your time and responses.
  2. I don't have the answer to your problem but just a few thoughts: do you really need such a short shutter time? When using flash the flash duration "stops the motion", so 1/200 + flash may do the trick. Depending on the distance a second flash closer to the action (or the 580 nearer to the dogs with a ST-E2 in the hotshoe) may provide enough light. The european Canon website has a downloadable copy of Flash Works, see this link.
  3. I think Jos has hit the nail on the head - maybe you don't understand flash photography basics?

    In flash photography, the function of the shutter is to open for long enough for the flash to fire. Unless the existing continuous lighting is very bright, which from your post doesn't seem to be the case, it doesn't matter within reason whether it's open for 1/30th or 1/250th, because there won't be enough continuous light to affect the exposure for the period of time that the shutter is open.

    The duration of the flash controls the length of the exposure, not the shutter, and accessory flashguns have an extremely short flash duration. You say that you can't afford big strobe units (I assume you mean studio flash) - well, small accessory flashguns will provide a much shorter flash duration anyway.

    If you REALLY do need a faster shutter speed then you need a camera fitted with leaf shutter, which will work at any flash speed, but we're talking about medium format cameras here, and medium format cameras with leaf shutters don't have extremely high shutter speeds so there may not be much benefit.

    I believe (not sure) that the Nikon D70 can work with very short shutter speeds when used with Nikon dedicated flashguns, and maybe your Canon can too. It might be worth looking into if you really do need fast speeds, but personally I doubt whether you do.

    Hope this helps
  4. First off, it sounds like you don't have enough light from your flash unit. Lose the silly diffuser. The Lightsphere and all other "tupperware" diffusers waste a lot of light by blasting it in all directions. If you do not have nearby reflective surfaces to return all that light to the subject's area, you have just lost the effectiveness of the flash unit.

    Like others have said, you don't need a fast shutter speed to "stop action". The burst of light from the flash is far faster than your 1/640 second.

    The easiest way to work would be to try the "P" exposure mode and just point your flash in the direction of the subjects. Use fully automatic mode on the flash unit. If you have a white wall or ceiling very near by, you could aim the flash to bounce the light off those surfaces for a softer look, but forget the "tupperware" for now.
  5. The other factor that I don't think anyone's mentioned on this thread is the max sync speed of the 30D - I think it's around 1/200th. That means that with any faster shutter speed the whole sensor is not ever totally exposed at the same moment - faster shutter speeds work by exposing a narrow strip that moves across the sensor. That means that a single flash will only illuminate a narrow strip of the image if you use a faster shutter speed.

    The 580 has a "high speed mode" that strobes the tube many many times that you can use with faster shutter speeds, but it reduces the effective output massively. And, as has been pointed out, in the dark you can basically use whatever shutter speed you like since the strobe duration is short enough to freeze any sensible movement.
  6. Also, many dogs are dark colored, and their fur benefits from direct flash, rather than diffused, especially for separation from dark backgrounds.
  7. The above picture is with a 70-200 F4, haven't done anything yet with the 24-70 2.8. I guess I get rid of the pics where the dog is in full gate, so this is the closest that I have. By the way, I am not in any way happy with this or any of the others that I have taken, so I'm not advertising this as quality, just an example of the environment and what I've done previously. So tips to make it better would be great. I have already ordered the book "Matters of Light" recommended in other posts. Thanks again.
  8. Aaron,

    We can't view your picture. The reason we ask people not to post pictures larger than 511 pixels wide - and not to post full-size pictures from digital cameras - is that apart from wasting bandwidth, people can't view them easily.
    Please resize the picture to not more than 511 pixels wide and post it again. Meanwhile, I'm deleting the post with the oversized picture
  9. Aaron, You've got quite good advice already. One important thing to remember (learn?) is that High Speed Sync is *NOT* High Speed Flash. Hotshoe flashes are quite fast when it comes to exposure times. A empirical study (http://www.waynesthisandthat.com/flashdurations.html) shows that the 580EX can have exposures as short as 1/35000s in its minimal power setting (1/128).
    Lesson to learn: The lower the power, the faster the exposure.
    To lower the output, you have three elements to optimize:
    • the flash-to-subject distance: the shorter the better
    • f/stop: the smaller the better
    • ISO: The higher the better (but compromise with image quality of course)
    • Your shutter speed should be kept above x-sync speed (1/200 or slower).
      The best way -for me- is to use Manual mode to have full control of all parameters.

      Try again and good luck!

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