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  1. #11
    NikoSperi's Avatar
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    Quote Originally Posted by Nick Zentena
    "Aiming the meter at the light source would not be a solution neither since the light the subject will refelct will be different."

    Maybe I misunderstood-) But he seems worried about reflection.
    Eh... somewhat. Not in the traditional sense of the black cat on the pile of coal and reflected reading. The problem with incident readings (flash or not) arises in backlit situations. Typically, one points the dome in the direction of the lens to take a reading that accounts for main light/fill lights etc that are roughly on the camera side of the subject. With the backlit (sunset, say), the incident reading becomes very tricky - where do you point the dome? Camera or light? That will make a huge difference, and is why I believe people invented spot metering flash meters!

    In short, I don't think the trouble was with the reflectance of the subject, but how to measure the light falling on it.

    PS: Oh, forgot... the Sekonic 308 is a great and very portable little meter. But the "spot" for reflected readings is something like 15 degrees, so don't expect it to do what it wasn't designed for. (Sold mine, and now might buy one back for portability reasons :rolleyes: )
    If you tone it down alot, it almost becomes bearable.

    - Walker Evans on using color

  2. #12
    rbarker's Avatar
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    To paraphrase the old saw regarding guns, incident meters don't kill good exposures, people do.

    As with the use of a reflective meter, the use of an incident meter requires both an understanding of what it's doing, and a (tested) method of interpreting the reading. Part of the interpretation is considering the lighting arrangement, and thinking about what portion of the subject illuminated by each light source is going to be seen by the lens. Then, adjustments can be made to the actual exposure to balance between the light sources (or, that process may suggest that the lighting needs to be changed or supplemented).

    When using an incident meter, I point the dome at the light source(s) from the subject position. Each of those readings will accurately render the portion of the subject illuminated by that source in it's true tonality - if that light source is treated as the main light. The "main" is usually the light source producing the strongest reading, but that can be varied depending on what you wish to create, what the ratios are, etc. As the angle between the lens axis and the light source increases, increasingly less of the illuminated area of the subject will be seen by the lens. Thus, adjustments to the exposure suggested by the meter reading may be desireable.

    Because the meter's dome may be seeing light from multiple sources, and will average between them, some care (or, shielding) is needed to discriminate between the multiple light sources. When all of the primary light sources are at less than 90° to the axis of the lens, i.e. on the "camera side" of the subject, it is that averaging process that prompts the usual recommendation to point the dome at the camera. For me, metering the light source, and then thinking about the lighting, produces better, more predictable results.

    Back lighting is obviously a special circumstance, as the portion of the subject illuminated by a light behind them won't be seen by the camera - only hair highlights, and such, that are really transmitted light from the lens's perspective.

    When mixing ambient light with flash, balance between them by using the f-stop to determine the contribution of the flash to the total exposure, and the shutter speed (at that aperture) to determine the contribution of the ambient light - within the limits of the shutter's sync speed, of course.

    Note, too, that other aspects of the overall exposure, development, and printing process also affect what is the optimal exposure for any given image. Thus, people who use different procedures in development or printing may also use different metering techniques. The trick is to establish a consistent metering procedure that works for you and your overall process and "vision".
    [COLOR=SlateGray]"You can't depend on your eyes if your imagination is out of focus." -Mark Twain[/COLOR]

    Ralph Barker
    Rio Rancho, NM

  3. #13

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    Another vote here for the Sekonic L-308B, fits bootifully in my pocket and easy to use without my glasses.

  4. #14

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    Thanks lads, some very usefull info here.

    The thread brought up one more question, when I set the meter in reflection mode and aim for the part of the subject I want to have the exposure based on it should be okay.
    But with a 20degrees reflective meter one should get closer to the subject to take a good measurement. Will this give the same result as using a 5deg meter from the same distance as the camera is?

    Something tells me this is different from the principle used with the flash lights getting closer or further away...

    And sorry for being a bit too analitical about this, but I just want to think about this now so it will become a neutral habbit in the future with a much higher succes ratio.

    cheers!

  5. #15
    David A. Goldfarb's Avatar
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    If you take a 20-deg. reflective reading up close, you should get the same result as if you take a 5-deg. reflective reading farther away of the same area. The only significant factor is the flash-to-subject distance.

    To think of a more extreme case--in general the exposure for a floodlit building at night is about 1/4 sec. at f:2 at ISO 400. On a clear night it doesn't matter if you are standing across the street and photographing with a wide lens or a mile away and using a long lens. The only issue is the distance between the lights and the building. The exposure does not change.
    flickr--http://www.flickr.com/photos/davidagoldfarb/
    Photography (not as up to date as the flickr site)--http://www.davidagoldfarb.com/photo
    Academic (Slavic and Comparative Literature)--http://www.davidagoldfarb.com

  6. #16

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    I used to have a client with a product that had deep, low-reflective black shelves and brushed chrome uprights. The customer wanted these on a white background for catalog use.

    Using a 1600 watt-second four light set-up shooting through 4' x 8' diffusion panels and a Minolta IV flashmeter in incident mode, I created a nightmare in the darkroom as I blasted the reflected light off of the brushed chrome blocking up the brushed chrome look or, alternatively dumped the white background into blotchy shadow that required tough up to print pure white.

    I solved this problem by going to a light-yellow seamless paper, using the 5 degree spotmeter attachment and metering off of the deepest blacks and adjusting development to hit the right level for the chrome. I then shot these using a #12 yellow filter (1.3 stop adjustment) which cleaned up the background. The negatives were an absolute dream to print!

    For me, this is the difference between incident light meters and reflective. An incident light meter will give you the "correct" exposure provided your subject is of "normal" contrast. Reflective light meters will tell you about your subject so you can chose an appropriate exposure and adjust your development (in the case of color transparencies) add or subtract light to hit the sweet-spot for contrast.

  7. #17
    rbarker's Avatar
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    The law of inverse squares applies only to light coming from the source because of its spread. The farther the source is from the subject, the less light that falls on the subject. Once it falls on the subject, and is reflected, exposure remains constant regardless of camera (or reflective meter) distance.

    With a 20°, or even a 5° reflective meter, one needs to be aware of what it is measuring, however. In most cases, a meter like that will be measuring both highlight and shadow values, and will give an averaged reading. That may be OK, or it might be misleading, depending on the subject's contrast, lighting ratios, etc. Personally, I prefer to take reflective readings with a 1° spot meter, so I can check the values for smaller areas, and thus keep all values within the capabilities of the film (or, the contrast range required by the presentation media, such as a magazine ad).

    Another key factor to keep in mind with all of this is that metering and exposure is all relative. That is to say, the values in the scene, and thus the exposure, are relative to each other. Thus, by lighting elements in the scene separately, one can adjust or manipulate the relative values, making them fall within the desired exposure and contrast range. That's what we're doing when we add "fill" (either with a reflector or a flash) to an outdoor portrait. That's also what we're doing by lighting a background separately from the main subject. If one can control the lighting, and the relative exposure values, a light-colored background can be made to appear much darker, or a dark background appear to be much lighter.
    [COLOR=SlateGray]"You can't depend on your eyes if your imagination is out of focus." -Mark Twain[/COLOR]

    Ralph Barker
    Rio Rancho, NM

  8. #18
    gr82bart's Avatar
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    A light meter is like a light sabre. Trust the forces within it and you will conquer the dark side.

    Art.
    Visit my website at www.ArtLiem.com
    or my online portfolios at APUG and ModelMayhem

  9. #19
    Michel Hardy-Vallée's Avatar
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    Funny, I misread the title and with the typo it gave me "Indecent Metering". Anybody practices that?

  10. #20
    rbarker's Avatar
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    Quote Originally Posted by mhv
    Funny, I misread the title and with the typo it gave me "Indecent Metering". Anybody practices that?
    I shoot nudes, and I think Morten does fetish work, but I don't think either is indecent.
    [COLOR=SlateGray]"You can't depend on your eyes if your imagination is out of focus." -Mark Twain[/COLOR]

    Ralph Barker
    Rio Rancho, NM

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