Exposure Near and Far - incident-light meter

Discussion in 'Digital Photography' started by Jack, Jul 3, 2005.

  1. Jack

    Jack Guest

    Hi
    When using an incident-light meter, holding it at or near the subject and
    aiming the meter's light-sensitive cell back toward the camera.
    I notice a difference when shooting at 10 ft and when shooting at 20 ft.
    Say when shooting at 10 ft I need to give it f8 but when taking the same
    shoot from 20 ft the shot is under exposed.

    Is this a known problem or am I doing something wrong?

    Thanks
    J
    Jack, Jul 3, 2005
    #1
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  2. Jack

    dylan Guest


    > Say when shooting at 10 ft I need to give it f8 but when taking the same
    > shoot from 20 ft the shot is under exposed.


    Is that just underexposed or underexposed relative to the 10ft shot ?
    Any chance of posting example pics to a website ?
    dylan, Jul 3, 2005
    #2
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  3. Jack

    Roy Guest

    "Jack" <> wrote in message
    news:da8e0g$ra7$-infra.bt.com...
    > Hi
    > When using an incident-light meter, holding it at or near the subject and
    > aiming the meter's light-sensitive cell back toward the camera.
    > I notice a difference when shooting at 10 ft and when shooting at 20 ft.
    > Say when shooting at 10 ft I need to give it f8 but when taking the same
    > shoot from 20 ft the shot is under exposed.
    >
    > Is this a known problem or am I doing something wrong?
    >
    > Thanks
    > J
    >

    Hi there.

    You are probably doing something wrong, or the meter is faulty.

    An incident meter measures the light falling on the subject, and an exposure
    set to the meter readings will be correct, irrespective of the Camera to
    subject distance.

    There could be areas in the picture which are not under the same lighting
    conditions as the part at which you were metering, but by definition these
    must be less important than the main subject, and it should not matter if
    they are incorrectly exposed. At the longer distance these might well
    occupy a larger portion of the frame, and give the impression that the
    picture is incorrectly exposed, but the main subject should still be
    correctly exposed.

    Are you setting the camera to the meter readings, using Manual Mode?

    Do you have the little dome or diffuser over the meter cell when taking the
    readings?

    I hope this might help.

    Roy G
    Roy, Jul 3, 2005
    #3
  4. "Jack" <> writes:

    > Hi
    > When using an incident-light meter, holding it at or near the subject and
    > aiming the meter's light-sensitive cell back toward the camera.
    > I notice a difference when shooting at 10 ft and when shooting at 20 ft.
    > Say when shooting at 10 ft I need to give it f8 but when taking the same
    > shoot from 20 ft the shot is under exposed.
    >
    > Is this a known problem or am I doing something wrong?


    When you move back, are you using the same lens set the same (and
    hence including a wider view), or are you changing lenses? Because if
    you're changing or resetting your lens, obviously there's another
    variable (and remember that zooms these days often change aperture,
    getting smaller as the focal length increases).

    If you're using the same lens at the same setting, is the *part* of
    the subject that's in the close picture exposed the same in the far
    picture? And are you judging this based on lab prints, or from the
    original film? If the additional subject that shows in the shot from
    further away is lit differently, it could change the subjective
    impression of the exposure, or in the case of lab prints even change
    how the print was made.
    --
    David Dyer-Bennet, <mailto:>, <http://www.dd-b.net/dd-b/>
    RKBA: <http://noguns-nomoney.com/> <http://www.dd-b.net/carry/>
    Pics: <http://dd-b.lighthunters.net/> <http://www.dd-b.net/dd-b/SnapshotAlbum/>
    Dragaera/Steven Brust: <http://dragaera.info/>
    David Dyer-Bennet, Jul 3, 2005
    #4
  5. "Jack" <> wrote in message
    news:da8e0g$ra7$-infra.bt.com...
    > Hi
    > When using an incident-light meter,


    Did you use the lumisphere (dome)?

    > holding it at or near the subject and aiming the meter's light-
    > sensitive cell back toward the camera.


    That should work if the light and bottom coverage is similar between
    positions.

    > I notice a difference when shooting at 10 ft and when shooting at 20
    > ft.


    Was the bottom coverage similar, did the light change (clouds)?

    > Say when shooting at 10 ft I need to give it f8 but when taking
    > the same shoot from 20 ft the shot is under exposed.


    What was the difference in read-out between measurements, and did the
    light change? This also means, did you stand behind the light meter
    (to avoid your clothes reflecting on the lumisphere), or did you cast
    a shadow?

    Bart
    Bart van der Wolf, Jul 3, 2005
    #5
  6. Jack

    Neil Ellwood Guest

    On Sun, 03 Jul 2005 14:41:48 +0000, Roy wrote:

    > "Jack" <> wrote in message
    > news:da8e0g$ra7$-infra.bt.com...
    >> Hi
    >> When using an incident-light meter, holding it at or near the subject and
    >> aiming the meter's light-sensitive cell back toward the camera.
    >> I notice a difference when shooting at 10 ft and when shooting at 20 ft.
    >> Say when shooting at 10 ft I need to give it f8 but when taking the same
    >> shoot from 20 ft the shot is under exposed.
    >>
    >> Is this a known problem or am I doing something wrong?
    >>
    >> Thanks
    >> J
    >>

    > Hi there.
    >
    > You are probably doing something wrong, or the meter is faulty.
    >
    > An incident meter measures the light falling on the subject, and an exposure
    > set to the meter readings will be correct, irrespective of the Camera to
    > subject distance.
    >
    > There could be areas in the picture which are not under the same lighting
    > conditions as the part at which you were metering, but by definition these
    > must be less important than the main subject, and it should not matter if
    > they are incorrectly exposed. At the longer distance these might well
    > occupy a larger portion of the frame, and give the impression that the
    > picture is incorrectly exposed, but the main subject should still be
    > correctly exposed.
    >
    > Are you setting the camera to the meter readings, using Manual Mode?
    >
    > Do you have the little dome or diffuser over the meter cell when taking the
    > readings?
    >
    > I hope this might help.
    >
    > Roy G

    There is another effect with the amount of moisture in the air, at short
    distance it could be unnoticed but with icreasing distance become very
    much more important by softening the image.

    --
    neil
    delete delete to reply
    Neil Ellwood, Jul 4, 2005
    #6
  7. Jack

    Jack Guest

    Thank you all for your kind replies

    You have given me plenty of homework. But I'm reassured that the f stop
    SHOULD remain the same at any given distance and that if there is a problem
    then I should be looking at other things.

    I thank you all for your valuable time.
    J
    Jack, Jul 4, 2005
    #7
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