Exposure compensation with flash

Discussion in 'Beyond the Basics' started by Big Mike, Oct 1, 2004.

  1. Big Mike

    Big Mike I am Big, I am Mike Staff Member Supporting Member

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    I'm trying to get this figured out in my head.

    Lets say I'm shooting a bride and I want to make sure the dress is white. Normally I would take a reading and open up (or slow down) an extra stop or two.

    Now if I'm using a flash...I'll have the shutter to the sync speed 1/125...and the aperture set to match my flash setting (either F4 or F8) lets say F4.

    I like to set the ISO on the flash 1 or 1.5 stops faster so that the flash is not over powering. By doing this do I get less exposure? (the opposite of what I wanted)

    Could I compensate the exposure by changing the aperture away from the setting on the flash? Is this the same as changing the ISO on the flash?

    Is compensating the flash the same as compensating the exposure?

    Am I on crack: :?

    I've never had any problems but I shoot print film and my lab does a good job so I'm not quite sure if my exposure is "right" or if they are fixing it for me.
     
  2. ksmattfish

    ksmattfish Now 100% DC - not as cool as I once was, but still

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    I don't know the specifics of your flash. Changing the ISO on any of my flashes doesn't actually do anything to the power of my flashes; it just adjusts the chart that tells me what f/stop to use (probably using the fomula GN/distance to subject=f/# @ ISO 100). If you are using your flash on manual then you should be getting the same light output each time, so metering is not necessary for your flashed subject. If you are using your flash on auto then it's probably too complicated for me :lol:

    Here's how I would do it with my Vivitar 285 flashes and any camera:
    use distance to subject to determine f/stop (the Viv 285s have 4 power outputs, so I have 4 choices of f/stops).
    if I wanted to under expose 1 stop then I'd close the aperture 1 stop from the original setting
    meter background for shutter speed using chosen f/stop
     
  3. Big Mike

    Big Mike I am Big, I am Mike Staff Member Supporting Member

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    Thanks Matt,

    I really don't have my head wrapped around manual flash settings. In most cases my flash to subject distance changes for every shot so I don't know if I could keep calculating that at all times.

    I do use the flash on Auto, set to either of the two setting F4 or F8...and with the ISO set one stop faster.

    I wish I had a digital so I could see the results of changing the settings immediately.

    I guess I should leave well enough alone. It just bothers me that I don't know and haven't figured it out yet. :?
     
  4. Danc

    Danc TPF Noob!

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    my photos turned out all color washout, overexposed and unsharp. as i never encounter this b4, so i cant figure out wat had happened. I used -1/2 stop EC (underexpose) for whole roll of film while using flash. any possibilities of this setting causing tat problem? I'm using EOS 300 wf kit lens. Wil adjusting the Exposure compensation effect pic quality? or its caused by bad film, developer error or lense fault?
     
  5. Big Mike

    Big Mike I am Big, I am Mike Staff Member Supporting Member

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    Try posting your question in a new thread. If you can post an example, that would help a lot. Also, try a spell check.
     
  6. Lol999

    Lol999 TPF Noob!

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    Hi Mike, if i work this out right you are effectively using the flash as a bit of fill-in to highlight the dress which should work out just fine. I agree with you on the digital bit, even though I'm a film addict the chance to view the results there and then would be great. And no, I can't afford a polaroid back!
     
  7. DocFrankenstein

    DocFrankenstein Clinically Insane?

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    Mike - how about you tell us what camera and what flash you're using for starters
     
  8. Big Mike

    Big Mike I am Big, I am Mike Staff Member Supporting Member

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    Well, when I started this thread, back in 2004, I was using a Canon EOS 650.

    Now I'm using a Canon EOS 20D, and I have a better idea of what I doing with flash...the instant feed back is a great learning tool.
     
  9. DocFrankenstein

    DocFrankenstein Clinically Insane?

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    oh @#$%@ old threads
     
  10. Big Mike

    Big Mike I am Big, I am Mike Staff Member Supporting Member

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    Happens to the best of us ;)
     

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