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Thread: Some Qns on Flash and Metering

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    Default Some Qns on Flash and Metering

    Hi there guys,
    I am pretty new to using flashes, just got my first external flash which is a Yong Nuo 560 II manual flash.
    I have tried using the flash yesterday for a convention (Cosfest 2014) and have a few questions/problems i ran into..
    First i understand that most people use manual mode when shooting with manual flash to get more consistent results, at first i was using manual and tweaked the settings to get a nice exposure, however, i realise that using manual mode means the settings i tweaked would only work for that specific focal length. For eg, if i tweak setting for 35mm and after that change to 50mm, the flash power may not be enough, or if i change to 24mm, the flash may turn up too bright. (the aperture is fixed when i change the focal length)
    Is there a trick to control this? I have tried reducing flash power but i ran into a problem where i reached the lowest flash power so i resort to using exposure compensation but using this makes pictures look unnatural.

    In the end i used Aperture priority mode and adjust the flash power instead, but this usually gives me pretty slow shutter speeds (the event was indoors with pretty dim lighting) which may have camera shake.

    Another question is about metering,
    When i was using the manual flash, i found that the default evaluative metering makes pictures look unnatural so i switched to spot metering, aim the center AF point on the face and locking focus/exposure, recompose, then take a shot.
    Would like to confirm if this is the correct way to use spot metering?

    Appreciate all the advise that you guys can give me, a newbie to flash photography and its been awhile that i decided to learn the other metering modes as well.

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    Default Re: Some Qns on Flash and Metering

    - The 'zoom' on the flash controls the 'spread' of the light. I believe it's that, the flash zoom at 50mm was unable to hit the other parts of the frame when you are shooting at wider focal lenght like 35mm or 24mm.

    - There are a few factors that might be causing the 'unnatural' photo. Upload a photo to illustrate what you mean.. But from my guess is that White balance may be one of it. The lights indoor and the daylight flash you are firing is different.

    - Metering...When using manual flash, I've only used the metering for the ambient light (not the subject) Not the subject. After you know how much ambient light you want, then you can decide how much fill flash you need. But given the situation in Cosfest, I can't imagine trying to meter the ambient where there are so many people walking past every moment.
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    It's almost impossible to judge on the fly the right amount of manual flash power needed with manual exposure control.

    The next alternative is to remember the flash guide number table for the flash you are using, it is a rough exposure guide.

    Best is to get a exposure / flash meter if you wish to go completely manual with your flash & exposure.

    As for event shoots most photog will use manual exposure with auto ISO but the flash will still be in TTL mode. This way the exposure meter in the camera is used to determine the flash power automatically from the pre flash, leaving the photog to adjust the aperture & needed shutter speed on the fly. Also some photog will use the bracketing function to bracket shots with varying degrees of compensated flash EV.

    Yes, you are correct on the use of the spot metering.
    Last edited by Light Machinery; 21st December 2014 at 12:06 PM.

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    Default Re: Some Qns on Flash and Metering

    Using manual flash control and manual exposure settings for an event is simply using the wrong tool. When people say that they use manual flash / manual exposure then they have a reason, the knowledge and the situation that calls for it. As long as you don't have the same conditions and knowledge there is no point to copy this. Finally, you want the pictures, right? (Of course, you can use such an event for experiments, but with such fast changing conditions it is really hard to do any useful and structured testing.)
    As you have noticed: Your camera and flash are much faster than you in determining the correct exposure values and flash exposure for the given light conditions, especially when they are changing quickly. So leave it to the camerasyst em to do this, focus on composition and watch out for the lights.

    Here some basic stuff to read up before you start with manual.
    - Standard exposure (exposure triangle) and the exposure metering (evaluative, center, spot etc): http://www.clubsnap.com/forums/showthread.php?t=309544
    - Flash exposure using TTL for your camera system (Canon works different than Nikon, so read the system specific details). Here for Canon: http://photonotes.org/articles/eos-flash/
    - A general guide that applies to all flash lights: I found: http://strobist.blogspot.sg/2006/03/lighting-101.html
    From the last link you will get to the point of balancing flash light and ambient light. That's the point where manual settings can come in. But again; this is done for a specific reason which is explained.
    EOS

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    Default Re: Some Qns on Flash and Metering

    Quote Originally Posted by SkyStrike View Post
    - The 'zoom' on the flash controls the 'spread' of the light. I believe it's that, the flash zoom at 50mm was unable to hit the other parts of the frame when you are shooting at wider focal lenght like 35mm or 24mm.

    - There are a few factors that might be causing the 'unnatural' photo. Upload a photo to illustrate what you mean.. But from my guess is that White balance may be one of it. The lights indoor and the daylight flash you are firing is different.

    - Metering...When using manual flash, I've only used the metering for the ambient light (not the subject) Not the subject. After you know how much ambient light you want, then you can decide how much fill flash you need. But given the situation in Cosfest, I can't imagine trying to meter the ambient where there are so many people walking past every moment.
    Hi, thanks for the advise. My problem with images looking "unnatural" was because some parts of the skin are blown out. I'm not sure if i am aiming the flash correctly. I am using a simple white plastic diffuser over the flash and aiming the flash directly at the model, as the ceilings were too high and I cant seem to find anything to bounce off the flash. I have seen some people aiming their flash at 45 degree angle though.

    Quote Originally Posted by Light Machinery View Post
    It's almost impossible to judge on the fly the right amount of manual flash power needed with manual exposure control.

    The next alternative is to remember the flash guide number table for the flash you are using, it is a rough exposure guide.

    Best is to get a exposure / flash meter if you wish to go completely manual with your flash & exposure.

    As for event shoots most photog will use manual exposure with auto ISO but the flash will still be in TTL mode. This way the exposure meter in the camera is used to determine the flash power automatically from the pre flash, leaving the photog to adjust the aperture & needed shutter speed on the fly. Also some photog will use the bracketing function to bracket shots with varying degrees of compensated flash EV.

    Yes, you are correct on the use of the spot metering.
    Quote Originally Posted by Octarine View Post
    Using manual flash control and manual exposure settings for an event is simply using the wrong tool. When people say that they use manual flash / manual exposure then they have a reason, the knowledge and the situation that calls for it. As long as you don't have the same conditions and knowledge there is no point to copy this. Finally, you want the pictures, right? (Of course, you can use such an event for experiments, but with such fast changing conditions it is really hard to do any useful and structured testing.)
    As you have noticed: Your camera and flash are much faster than you in determining the correct exposure values and flash exposure for the given light conditions, especially when they are changing quickly. So leave it to the camerasyst em to do this, focus on composition and watch out for the lights.

    Here some basic stuff to read up before you start with manual.
    - Standard exposure (exposure triangle) and the exposure metering (evaluative, center, spot etc): http://www.clubsnap.com/forums/showthread.php?t=309544
    - Flash exposure using TTL for your camera system (Canon works different than Nikon, so read the system specific details). Here for Canon: http://photonotes.org/articles/eos-flash/
    - A general guide that applies to all flash lights: I found: http://strobist.blogspot.sg/2006/03/lighting-101.html
    From the last link you will get to the point of balancing flash light and ambient light. That's the point where manual settings can come in. But again; this is done for a specific reason which is explained.
    Thanks for the comments from you all and the links Octarine, my problem is that the flash (Yongnuo 560 II) is manual only with no TTL, so i must set the power myself. Since i mentioned it was too much hassle to shoot in manual and in the end i used Aperture priority mode, I was wondering if there are any workarounds to this problem, because Av mode gives slow shutter speeds which caused some images to be blurry and i would not want to push the ISO too high.

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    Quote Originally Posted by thegamer1907 View Post

    Hi, thanks for the advise. My problem with images looking "unnatural" was because some parts of the skin are blown out. I'm not sure if i am aiming the flash correctly. I am using a simple white plastic diffuser over the flash and aiming the flash directly at the model, as the ceilings were too high and I cant seem to find anything to bounce off the flash. I have seen some people aiming their flash at 45 degree angle though.

    Thanks for the comments from you all and the links Octarine, my problem is that the flash (Yongnuo 560 II) is manual only with no TTL, so i must set the power myself. Since i mentioned it was too much hassle to shoot in manual and in the end i used Aperture priority mode, I was wondering if there are any workarounds to this problem, because Av mode gives slow shutter speeds which caused some images to be blurry and i would not want to push the ISO too high.
    If some parts are blown out, just reduce the power more, or change ur camera settings to underexpose it.

    By any chance you are using Canon system? If you are, I recommend a good read at the article linked previously... it really explains why you are getting those results.

    For those aiming at 45degrees in that hall without any bounce cards, I think they might be just a lot of wasting power.


    Btw, still the best way to get around shooting in events is with a ttl flash. It's a different story if you have set up a "booth" in the event hall to shoot...
    Last edited by SkyStrike; 21st December 2014 at 01:44 PM.
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    Moderator catchlights's Avatar
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    Flash on manual mode work best is when your flash to subject distance is constant. You move here move there during a event, flash to subject distance keep changing, how do you expect the exposure of the flash light on your subject is the same thru out?

    Learn how to walk first before you start running. Just use flash TTL mode first and read up about flash photography.
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    Moderator catchlights's Avatar
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    Btw, if you insist on using manual power on flash, than try read and understand inverse square law of light, once you understand this law, with practise, you can get correct exposure on the fly.
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    Default Re: Some Qns on Flash and Metering

    I gained more insights on flash photography from the links. I think i was making a big mistake, i thought that shutter speed would affect how bright the flash would turn out. I guess that shooting more events will help me understand the flash better.

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    Quote Originally Posted by thegamer1907 View Post
    I gained more insights on flash photography from the links. I think i was making a big mistake, i thought that shutter speed would affect how bright the flash would turn out. I guess that shooting more events will help me understand the flash better.
    No, shutter speed has nothing to do with the exposure of flash. But aperture, and ISO do.
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    Default Re: Some Qns on Flash and Metering

    Quote Originally Posted by catchlights View Post
    No, shutter speed has nothing to do with the exposure of flash. But aperture, and ISO do.
    thanks, i will keep that in mind and experiment more in the future.
    Thanks for all the good advise guys, i shall close the thread.

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