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Thread: Aperture Priority & Flash = Confusion

  1. #1
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    Default Aperture Priority & Flash = Confusion

    Hi, I am still confuse with regard to setting Aperture Priority with flash activated.

    Settings:
    1. Using pop-up flash on D200
    2. ISO = 100
    2. Aperture priority = f8
    3. Shuttle speeds show = 30s

    Result:
    1. Electroninc Analogue Exposure Display show under expose = 2EV
    2. Picture take = under exposed

    Question:
    I thought once the flash is being used, either external or pop-up flash and is TTL it should take care of the exposure regardless of what aperture you set (that is the whole idea of aperture priority).

    In this case what is the correct way getting the right exposure with aperture priority?

    Thanks in advance for sharing.
    "Glory in his holy name, let the hearts that seek Yahweh rejoice!"

  2. #2

    Default Re: Aperture Priority & Flash = Confusion

    OOPS! Just saw that you were using your pop-up flash.
    Last edited by Dream Merchant; 16th October 2009 at 05:08 PM.

  3. #3
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    Default Re: Aperture Priority & Flash = Confusion

    by rite, the ttl flash should be able to take care of it to ensure it is evenly lit...

    BUT, ur scene is ultra too dark already. and ur settings at iso 100, f/8, and shutter speed of 1/30s is too tough for the flash to handle. as a result, even though ur flash has already blasted full blast, it is still not bright enuff to lit up, and as a result, u get under-exposed pic.

    solution 1:
    alternatively, dun use iso 100, use iso 200 or 400, use apeture of f6.3 or f5.6, and ur pic will also turn out fine, ur flash will be strong enough

    solution 2:
    However, if u use the same settings at a brighter location, ur pic will turn out fine

    solution 3:
    get an external flash
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  4. #4
    Moderator catchlights's Avatar
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    Default Re: Aperture Priority & Flash = Confusion

    built in flash of D200 has limited power, GN only 40 (ISO 100, 40feets)

    for ISO 100, f8, probably you are good to take a close up headshot, any subjects more than 5 feet away will be beyond the flash limit.

    btw, shutter speed has nothing to do for the flash exposure, time to read basic photography.
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    Default Re: Aperture Priority & Flash = Confusion

    the scene is too dark your flash is not strong enough, even firing at max power, and the camera Shuttle speeds (auto setting maximum)at 30s. f/8 will limit the light in, while ISO 100 is not sensitive enough to capture the scene.
    Last edited by zcf; 16th October 2009 at 05:16 PM.
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  6. #6
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    Default Re: Aperture Priority & Flash = Confusion

    By choosing aperature priority, it allows the user to choose a specific aperture value while the camera selects a shutter speed to match. It does not "automatically" expose the photo for you. It tries to compensate by setting the shutter speed, but your ISO is still set by you and therefore can limit what the camera can capture.

    So first and foremost, it is most evident that the aperature you have chosen (f8) may not be letting in enough light. The lower the aperature, the more light you let in, so try to set it to its lowest setting.

    Next, adjust the ISO to maybe 400 or 800 and see if any of that makes a difference.

    Good luck!

  7. #7
    Senior Member Diavonex's Avatar
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    Default Re: Aperture Priority & Flash = Confusion

    If picture is under-expose, you can either:

    1. increase the ISO to say 400 or 800 (increase sensitivity of sensor)

    2. open up the aperture futher e.g. F5.6, F4.0 or F2.8 (allow more light reaching the sensor)

  8. #8
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    Default Re: Aperture Priority & Flash = Confusion

    Thanks for all the feedback.

    OK, what if:

    I use an external like SB800 and with a preset aperture and the Electroninc Analogue Exposure Display shows under expose, do I need to make sure that it is properly exposed by either:
    (a) increase the ISO; or
    (b) open up the aperture

    Or just leave it and do not have to care about the reading shown in the Electroninc Analogue Exposure Display if the subject is within the flash cover distance ?

    Thanks.
    "Glory in his holy name, let the hearts that seek Yahweh rejoice!"

  9. #9

    Default Re: Aperture Priority & Flash = Confusion

    3. Shuttle speeds show = 30s
    Errr.... How do you use flash with such a low shutter speed?

  10. #10

    Default Re: Aperture Priority & Flash = Confusion

    Quote Originally Posted by PrimePhotog View Post
    Errr.... How do you use flash with such a low shutter speed?
    errr.... why not? i can still use flash with 5 sec shutter...

  11. #11

    Default Re: Aperture Priority & Flash = Confusion

    conversely its harder to use flash at higher shutter speeds.. either you can't sync at all or eat up alot of power trying to do high-speed sync, quite a warp logic I know..

  12. #12
    Moderator catchlights's Avatar
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    Default Re: Aperture Priority & Flash = Confusion

    Quote Originally Posted by Rejoice View Post
    Thanks for all the feedback.

    OK, what if:

    I use an external like SB800 and with a preset aperture and the Electroninc Analogue Exposure Display shows under expose, do I need to make sure that it is properly exposed by either:
    (a) increase the ISO; or
    (b) open up the aperture

    Or just leave it and do not have to care about the reading shown in the Electroninc Analogue Exposure Display if the subject is within the flash cover distance ?

    Thanks.
    Electroninc Analogue Exposure Display only meter for the ambient lights, with or with flash attach, if you want to make sure the scene exposed correctly with the ambient lights, you have to adjust the ISO, aperture and shutter speed accordingly, till the Electroninc Analogue Exposure Display indicate correct exposure.

    if you use flash for this scene, you have to decide whether to use the flash as main light or supplement light (Fill Light).

    For using flash as Main light, you can ignore metering for the ambient lights or keep the ambient lights one to two stops below the flash exposure (judging from the Electroninc Analogue Exposure Display)

    For using flash as Supplement lights (Fill Light), you need to exposed for the ambient lights, set your camera exposure setting according to the Electroninc Analogue Exposure Display recommendation, and use iTTL BL on flash, or iTTL with minus flash exposure compensation.
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  13. #13
    Moderator catchlights's Avatar
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    Default Re: Aperture Priority & Flash = Confusion

    if it is still very complicated to understand, you can borrow this book from our national library.

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    Default Re: Aperture Priority & Flash = Confusion

    Thanks for your feedback. Appreciate very much.
    "Glory in his holy name, let the hearts that seek Yahweh rejoice!"

  15. #15

    Default Re: Aperture Priority & Flash = Confusion

    Quote Originally Posted by catchlights View Post
    if it is still very complicated to understand, you can borrow this book from our national library.

    Hmm, thks..
    I'll also take a photo of books I borrow from library..lol
    BTW guys, popular books are also available..eg Hot Shoe Diaries, The moment it clicks, Understanding exposure...

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