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Thread: Flash photography setting - need help

  1. #1
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    Default Flash photography setting - need help

    Dear all,

    I am still exploring the full potential of flash photography. Need advice on a few questions, hope you are able to assist :

    Equipment – Canon 400D, Sigma 500 DG flash

    1. Once ETTL is locked in on the subject, will adjustment of speed, aperture or ISO affect the correct exposure of the subject? (Have been playing with the settings, unable to figure out how things work).

    2. How to shoot a night scene with a person as your subject yet with proper exposure of the night scene in the background?

    3. How to shoot a person as the subject with flash in the late afternoon (sunset) out door and intentionally under expose the background?

    4. Indoor photography with flash, what is the typical setting by most photographers?

    5. When a bounce card is use, do I have to increase the flash compensation?

    Thanks
    L.Lee

  2. #2

    Default Re: Flash photography setting - need help

    I am only able to provide some help to you with regard to the proper exposure of shooting people in night scenes. I am using Canon D400 with 580EX and I realised that every time I set the flash to auto, the power of the flash is so much that it whites out the people. I found out that setting the flash power manually to 1/4 works most of the time (depends on lighting available too). Important, ask your subject not to move until the shutter closes (when you tell them). I use direct flash since there is nothing to bounce nd I don't have other tools (eg: flashcard, lightsphere) yet..

  3. #3
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    Default Re: Flash photography setting - need help

    Thanks lawrenchoo, I am trying to read up some articles, but they are lengthy and do not provide a quick and direct answer . Still reading....

    In my case, if I set the mode to "P", it works well on exposure but I do not have control. Setting the speed sync at 1/200 also helps, but it will not achieve the effect I need as in scene (2) and (3) I mentioned earlier.

    Cheers.

  4. #4
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    Default Re: Flash photography setting - need help

    Hope I get this right.

    1. ETTL determines the correct amount of light that falls on the subject. However, if the subject is backlit, the ETTL sensor may still be fooled and give you the wrong exposure. Keep in mind that the flash will fire for only a fraction of a second, so even if you had used a longer exposure, the flash will only light the subject up during the initial 1/200s. If you used a larger aperture (or higher ISO), the exposure time is shorter, hence the flash to ambience ratio is higher (the effect of the flash is harsher), and if a smaller aperture or lower ISO is used, the background lighting will have a stronger effect.

    2. You need to use a slow sync flash, meaning a longer exposure to expose the background and use the flash to light up the subject.

    3. You will need to provide a strong flash output to compete with the brightness of the background. It is probably easier to let the background stay as it is and use a fill flash to light up the subject.

    5. I think canon ETTL only works if you are using direct flash or with a omnibounce.

  5. #5
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    Default Re: Flash photography setting - need help

    Hi Lee,

    Actually it's relatively easy.

    Canon DSLR with ETTL Flash on, in AV mode or Tv mode, will automatically expose for the background ambient light and controlled flash exposure on the subject automatically.

    Tried it out, alternatively, you can meter the background first, and lock the exposure, then let the ETTL flash do the work on the subject.

    Somethings, I will underexpose the background by 1 stop to make the subject stand out.

  6. #6

    Default Re: Flash photography setting - need help

    Quote Originally Posted by L.Lee View Post
    Thanks lawrenchoo, I am trying to read up some articles, but they are lengthy and do not provide a quick and direct answer . Still reading....

    In my case, if I set the mode to "P", it works well on exposure but I do not have control. Setting the speed sync at 1/200 also helps, but it will not achieve the effect I need as in scene (2) and (3) I mentioned earlier.

    Cheers.
    Why don't you just experiment with the settings for the senarios you outlined? There is no one settings or solutions to your veraious questions.

    Lengthy articles? They are lengthy because there are that many permutations. They are lengthy because they try to teach you the fundamentals. they are lengthy becasue they need to explain the fundamentals in laymen terms.

    Quick and direct answers? Seems the only thing people want these days. Quick and direct answers give you the knowledge, but not the skill.

    Learn the skill, you will know what to do in all the different situations.

    Quick and direct answers, what if it does not applies exactly, then how?
    Last edited by Deadpoet; 29th May 2007 at 01:10 PM.
    deadpoet
    my portfolio

  7. #7
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    Default Re: Flash photography setting - need help

    I manage to read up some articles, I got one here that answered my questions:
    http://photonotes.org/articles/eos-f...ndex.html#faq6

    This is what it says "In Av, night and Tv (shutter speed priority) modes the camera meters for ambient (existing) light and fills in the foreground subject using the flash. It does not assume that the primary light source is the flash, and therefore the shutter speed it sets is the same as it would set if you weren’t using flash at all. "

    Another useful article:
    http://www.planetneil.com/faq/flash-techniques.html

    Cheers

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