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  1. #1
    stradibarrius's Avatar
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    Reflective vs. incidence meter reading??

    I am trying once again to copy Keith's "pasta" shot. It is simple but it caught my eye and I felt like trying to duplicate the tone and contrast he captured.

    I set my lights and RB67 and pulled out my meter. The difference between the rel=reflective and incident is about 1-1/3 stops...Is it normal for the two types of reading to be different?
    Which will or should be more accurate?
    Or maybe the question should be when there is a discrepancy which would you choose?
    "Generalizations are made because they are generally true"
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    SuzanneR's Avatar
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    Depends on how you want to expose the film. Are you using a spot meter for the reflective reading? If it's an in-camera meter, I'd use the incident reading, but if you have a spot meter, then you can pretty much decide which part of the pic you will place at about 18% grey.

  3. #3
    stradibarrius's Avatar
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    I don't think I have ever seen a camera with an "incidence" meter built in????
    I am using a hand held analogue Gossen Digi-Pro.
    "Generalizations are made because they are generally true"
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    Barry
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    SuzanneR's Avatar
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    Sorry, I wasn't clear.

    If the reflective meter you are using is a spot meter, then that can give you a very accurate read. If it's in camera, and measuring the whole scene, then I would use the hand held incident meter, instead.

  5. #5
    markbarendt's Avatar
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    Incident meters measure the light falling on the scene and tell you the camera setting.

    If your incident meter is "pressed-against-the-tip-of-subjects-nose" with the dome is pointed at the camera lens; it will normally be right and reliable.

    Reflective meters require more thought because the reading is affected by the subject.

    If for example if your reflective meter was pointed at a white sheet of paper in your scene, the reflective meter reading may differ from the incident meter reading by 2-4 stops, black paper, same offset in the other direction.

    With the reflective meter you need to decide how to adjust the meter's reading based on what you read off of.

    What I'm saying is that the two readings you took may be telling you the same thing, you just haven't adjusted the reflective meter's reading yet.
    Mark Barendt, Ignacio, CO

    "We do not see things the way they are. We see things the way we are." Anaïs Nin

  6. #6

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    I always had trouble with incident-meter readings until I realized one simple fact. When pointing the meter at the camera, the camera has to be in the same light as the subject. IOW, if the camera is in different light, point the meter at a location in the same light as the subject as close as possible to the camera position.

  7. #7
    markbarendt's Avatar
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    Quote Originally Posted by tessar View Post
    I always had trouble with incident-meter readings until I realized one simple fact. When pointing the meter at the camera, the camera has to be in the same light as the subject. IOW, if the camera is in different light, point the meter at a location in the same light as the subject as close as possible to the camera position.
    I have to dis-agree.

    The meter has to be in the same light as the subject, the camera position makes no difference as long as it has a clear view.

    Further, in a studio setup with lights like stradibarrius is using, the meter needs to be right at the subject's nose because, depending on the lights, 6 inches or a foot of difference can create a full stop of change in the exposure indicated.
    Mark Barendt, Ignacio, CO

    "We do not see things the way they are. We see things the way we are." Anaïs Nin

  8. #8
    eddym's Avatar
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    Quote Originally Posted by tessar View Post
    I always had trouble with incident-meter readings until I realized one simple fact. When pointing the meter at the camera, the camera has to be in the same light as the subject. IOW, if the camera is in different light, point the meter at a location in the same light as the subject as close as possible to the camera position.
    The light on the camera is irrelevant. With an incident meter, you should read the light falling on the subject. After all, that's what you are taking a picture of... not the camera!
    Eddy McDonald
    www.fotoartes.com
    Eschew defenestration!

  9. #9

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    The short answer is that, unless you were making the reflected light reading from a standard gray card, you should expect the readings to be different. The reflected light reading takes the intensity of light within the field of view and, in effect, arrives at the setting required to produce that light intensity as "standard gray." If the object being read is black - you still get gray; if white- you still get gray.
    The incident light reading measures the amount of light falling on the object and, in effect, calculates an exposure which would correlate to a reading made - in the reflected light mode - of a standard gray card.

    The incident light reading, executed properly, will normally tend to render the scene fairly accurately (assuming normal development) while the reflected light reading will depend on the angle of view of the meter (spot or wider angle), tonality and reflectivity of the object surface measured.

  10. #10
    Lee L's Avatar
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    The kind of light the camera is in makes no difference at all when reading with an incident meter. What matters is that the meter is in the same light as the subject, and pointed toward the camera. Note that with studio lighting, and especially with lights close to the subject, you should have the meter as near as possible to the subject to avoid the effects of light falloff, which can be significant with small changes of position relative to a close light source.

    APUG could use some tutorials on the fundamentals:

    From Kodak: http://www.kodak.com/cluster/global/...ex.shtml#54503
    .pdf at http://www.kodak.com/global/en/consu...ts/pdf/af9.pdf
    USING INCIDENT-LIGHT METERS

    To use an incident-light meter, hold it at or near the subject and aim the meter's light-sensitive cell back toward the camera. The meter reads the amount of light illuminating the subject, not light reflected from the subject, so the meter ignores the subject and background characteristics. As with a reflected reading, an incident reading provides exposure information for rendering average subjects correctly, making incident readings most accurate when the subject is not extremely bright or dark.

    When taking an incident-light reading, be sure you measure the light illuminating the side of the subject you want to photograph, and be careful that your shadow isn't falling on the meter. If the meter isn't actually at the subject, you can get a workable reading by holding the meter in the same kind of light the subject is in. Because the meter is aimed toward the camera and away from the background light, an incident reading is helpful with backlighted subjects. This is also the case when the main subject is small and surrounded by a dominant background that is either much lighter or darker.

    The exposure determined by an incident-light meter should be the same as reading a gray card with a reflected-light meter. Fortunately, many scenes have average reflectance with an even mix of light and dark areas, so the exposure indicated is good for many picture-taking situations. However, if the main subject is very light or very dark, and you want to record detail in this area, you must modify the meter's exposure recommendations as follows:

    For light subjects, decrease exposure by 1/2 to 1 stop from the meter reading.
    For dark subjects, increase exposure by 1/2 to 1 stop from the meter reading.
    You will notice that these adjustments are just the opposite from those required for a reflected-light meter. An incident meter does not work well when photographing light sources because it cannot meter light directly. In such situations you will be better off using a reflected-light meter or an exposure table.

    If the scene is unevenly illuminated and you want the best overall exposure, make incident-light readings in the brightest and darkest areas that are important to your picture. Aim the meter in the direction of the camera position for each reading. Set the exposure by splitting the difference between the two extremes.
    Last edited by Lee L; 02-06-2010 at 03:40 PM. Click to view previous post history.

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