flash help

Discussion in 'Beyond the Basics' started by Freedbaby, May 26, 2008.

  1. Freedbaby

    Freedbaby TPF Noob!

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    was at a wedding last night and the photographer happened to be a family friend so he didnt mind my picking his brain when he sat for a break.

    It was a dark reception hall and he was getting amazing results using his flash by bouncing it in various places.

    Here is what I DONT get. He was shooting at ISO 800, F5.6 at 125th. I pulled out my camera and set it to the same settings and the meter was flashing at the -2....basically telling me that the shot was going to be waaay under exposed but it came out perfect. If you are not so good to be able to just look at the light in a room and make a judgement call, how do you meter or guage for this??

    I have looked at strobist and the EOS flash website but they seem to be either very technical or directed at people using off camera strobes and umbrellas....for portraits and studio work.

    I shoot a Cannon 40D, usually have on a Tamron 17-50 F2.8 and a 430EX flash.

    Any help is appreciated.

    Freedbaby
     
  2. Big Mike

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

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    Here's the deal.

    Your camera's meter only reads the ambient light. So when you input those settings...the meter is off the scale (probably more than just -2). That's OK because the flash will pick up the slack.

    Your flash & camera have 'E-TTL' metering, which means that the flash will fire a preflash, read that, then adjust the power to be appropriate for the aperture. (flash exposure is only affected by flash power, aperture and ISO (not shutter speed)).

    So that takes care of the exposure for the subject (or whatever the flash is lighting up). You can then adjust the settings so that any ambient lighting is recorded or not. A longer shutter speed, a bigger aperture or a higher ISO will give you more ambient exposure.

    So if you haven't figured it out yet...in this situation, I would shoot in manual mode and pretty much forget about what the meter is reading.

    Also, you can tune the exposure by changing the FEC (flash exposure compensation). It might need to go up or down, depending on what is reflecting the light.
     
  3. Freedbaby

    Freedbaby TPF Noob!

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    I sorta get it. I later took another shot with it metered properly (acording to the camera) and it looked horible. Shouldnt the ambient light exposed properly come out ok??

    Freedbaby
     
  4. Big Mike

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

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    Maybe...but it depends.

    Firstly, an ambient only exposure in a dark hall will probably require a long shutter speed...which will cause blur from camera and/or subject movement. You might also have needed a high ISO, which will add noise. Also, the camera's meter is set for mid tone (18% grey) and if the scene is darker than that, then you need to adjust the exposure away from the meter, to get accurate exposure.

    There there is the issue of lighting type and temp. The WB may not have been set correctly for the light, or there may have been different light temps, which will cause somthing to be off and cause a color shift.

    Maybe show us an example with the shot data.
     
  5. Freedbaby

    Freedbaby TPF Noob!

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    The bad was that it was just blown out....I dont think it had anything to do with the WB or anything. It just seemed to have way too much flash(the shot I tried to expose properly that is).

    I think you said the magic words in your first reply, basically in a situation like that the meter isnt going to help. I assume the right answer is "you just have to gain experience and know"

    still having a hard time not being able to quantify it though...

    Freedbaby
     
  6. Big Mike

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

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    Ah yes...it can get pretty tricky when trying to mix flash and ambient...and sometimes it's hard to predict what E-TTL is going to give you.

    Practice and experience will be the key to learning this. It's one thing to explain it...but until you do it and see the results first hand, it can be hard to really 'get it'.

    So keep at it.
     

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