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Thread: Slow Sync Flash

  1. #1

    Question Slow Sync Flash

    Just like to find out when should I use slow sync flash.

    My C2040Z offers 2 kind of slow sync flash:

    1. Fires flash during first half of the time the shutter is open

    2. Fires the flash during the second half and fires a preflash b4 the main flash fires.

    When I normally took group pictures of my friends and colleagues, my C2040Z flash will often ruined the picture with a whitish outcast. So will a slow sync flash resolve this problem? Or is it not even suitable for taking potraits shots?

    Thanks for any assistance

  2. #2

  3. #3

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    Paiseh, I missed this the first time round. Actually I don't know what you mean by the white cast leh....can post a sample to see? Slow sync is usually for taking people against a dark background, for example, someone standing against the CBD skyline as the background at night. So slow sync will fire a flash to illuminate your human subjects and open the shutter longer so that the background can show up nicely. I don't think it will be useful to prevent a white cast lor...

    definitely will be useful if you can post a sample pic.

  4. #4
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    when you say a "white cast", could it be the WB setting? Setting to a warmer setting (e.g. sunlight) might improve the pic.
    Check out my wildlife pics at www.instagram.com/conrad_nature

  5. #5

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    Thanks for the reply, KC and Tweek

    For the white cast, means that the flash tends to illuminate the subject too much, thus making the subjects losing their original colours and becoming too "shiny" or "white".

    And if I dun use flash, my cam will tend to open the shuttle longer thus the image will sometimes be blurred

    Will like to post some samples but I think my friends will kill me for it hee.

    Does adjusting the W/B also lower the effect of the flash too?

    Thanks again!

  6. #6
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    Originally posted by Blitz

    Does adjusting the W/B also lower the effect of the flash too?
    changing the W/B could make the pic appear warmer (less white cast). but if the pic is overexposed, I don't think there's much it could do.

    of course, you could use Photoshop tricks by increasing the saturation of colors.
    Check out my wildlife pics at www.instagram.com/conrad_nature

  7. #7
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    Hee hee... I think you mean the flash resulting in over exposure with all the hot spots appearing white... Appears to be a common problem with consumer digital cameras that lacks the 3D matrix flash metering on SLR of a certain make (Er... Nikon righ?). The problem occurs when the flash is fooled and fails to regulate the flash output properly.. I notice it occurs especially often when the background is very dark and there is nothing to reflect back the flash in the background. I believe this is because the camera measures the exposure by the flash using the bckground, resulting in the foreground being over exposed. That's my theory, I haven't been very successful in finding a solution that does not involve requiring a flash with manual controls. Ever tried switching to spot metering and making sure that the spot is on one of the subject's face? Could be useful if the flash measures the output using the same position as the camera's light meter...

  8. #8
    Trevor_Tan
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    Originally posted by Blitz
    For the white cast, means that the flash tends to illuminate the subject too much, thus making the subjects losing their original colours and becoming too "shiny" or "white".

    And if I dun use flash, my cam will tend to open the shuttle longer thus the image will sometimes be blurred

    Will like to post some samples but I think my friends will kill me for it hee.

    Does adjusting the W/B also lower the effect of the flash too?

    Thanks again!
    Sorry, Didn't know what type of camera or DC u use, but mainly I think your flash is too bright. There is a few ways to solve the problem but not sure your camera can handle.
    One way is to change the place, try take picture in a place which is more bright (near a street light or any light sources)
    If your camera flash have -/+EV compensation then use it to reduce the flash brightness.
    Try to meter at a brighter object that is same distance away from the person u shooting. (white shirt, etc)
    One of the easier way is to have the object standing further away from the camera.
    One last way I can think of (normally what I did for compact camera) is to use a layer of tissue paper (how thick will depend on how strong your flash is) and only cover it over the flash (careful not to cover the lens or other metering stuffs). This will act as a defuser and reduce the brightness.

    This are some of the stuffs that I will try but if it will work for you it is up to you to try it out.

    Good luck!

  9. #9
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    I was thinking... another reason why consumer digital cameras have this problem is because it determines the flash output with a preflash...

    So let's say you focus and then recompose, when you recompose, the spot where the light is metered has been moved out, maybe ending up pointing at something darker. so when the preflash fires, it measures and compute the flash output on this darker area and resulting in a flash that is too powerful.

  10. #10

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    Thanks for all the replies!

    I'm using a C2040Z Trevor.

    Hmm seems that there's a limitation to this problem using a digital cam is it?

  11. #11
    Trevor_Tan
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    Originally posted by Blitz
    Thanks for all the replies!

    I'm using a C2040Z Trevor.

    Hmm seems that there's a limitation to this problem using a digital cam is it?
    Sorry missed your model number in the first message. Anyway I read thru a review on your camera in the net (http://www.dcresource.com/reviews/ol...c2040z-review/) and understand that your camera had "Flash exposure compensation". The logo with bolt & +/- sign. Play with it, it should reduce the strength of the flash if you set it to negative.

    The "one touch" white balance mode in your camera may be can be use to tell the camera what is consider as white during the time of shoot. (meaning you must always bring a white card around)

    Also "AE Lock" also seem to be quite useful also.

    Good Luck in your research!

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