metering with incident light meter

Discussion in 'Lighting' started by krisb1981, Nov 8, 2013.

  1. krisb1981

    krisb1981 Member

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    This has been on my mind for a while now and it seems like there are as many anwsers as there are people. When you meter portrait lighting (3) lights, you would point the meter's dome at the camera since it (dome) simulates 3D object such as human face and it averages lights from all three sources. My main issue is when you only have one light, let's say a shop 500 Watt daylight balance bulb in 10 inch relfector for strong contrasty look. Where do you point the meter's dome? At the light source? or at the camera? I have asked about it and have read about it but what I get is 50/50. Some say point it at the light, some to point it at the camera. Which is it? I want to shoot some 4x5 portraits with one light and would like to know where to meter.
    Thank you
     
  2. BainDarret

    BainDarret Subscriber

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    For a contrasty look point the dome at the light source.

    Invest in 2 sheets of film and try both methods and see which suits you.

    Mike
     
  3. BrianShaw

    BrianShaw Member

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    In general, point at the camera. If you want to assess lighting ratios in a multi-light situation, point at each light source. There is an old method called "duplex metering method" that you may want to investigate - that is generally when one points an incident at lights rather than at the camera. Any good book on photographic exposure, especially if published around the 1950s or 60s will have such discussion. It was most often associated with flat diffusers rather than the hemisperical dome diffusers, or highly contrasty situations.
     
  4. BrianShaw

    BrianShaw Member

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    p.s. a cheap, but authoritative, read on this topic if you search the old book sites is: Exposure Manual by Dunn and Wakefield
     
  5. cliveh

    cliveh Subscriber

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    Light meter readings, whether incident or reflective should only be taken as a guide and not read verbatim. Only by repeated experience with the same film/process and lighting variations will you gain the look you are seeking. I know you could also experiment with the film and process, but I’m trying to help without too many variables.
     
  6. Alan Gales

    Alan Gales Subscriber

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    From what I have read you can do either. Some prefer facing the camera and some prefer facing the main light. Some do like Brian mentioned and do multiple readings. The main thing is consistency. Pick one method and always use that.

    For what it's worth I have my dome face the camera. Of course I'm not a Pro so you are getting an amateurs opinion but my portraits do come out nice like I'm sure Brian's do also.
     
  7. markbarendt

    markbarendt Subscriber

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    Orienting the head differently measures different things with the incident meter. It can be used to determine exposure settings, or can be used to determine contrast ratio.

    Pointing an incident meter at the camera gives you a reading of the light that is "falling on the scene the camera can see" and that reading will place subject exposure to look "normal" under that light. This normally ensures a camera setting that provides good detail on both sides of the face.

    Pointing the meter at the main light source will make the dark side of the face look very dark. Pointing the meter away from the main light source will make the Darkside look brighter. You can use any angle in the middle to determine how bright or how dark you want the subject to look.

    That is all about placement, contrast is a different matter.

    To measure contrast I normally retract the dome.

    Pointing the meter at the main light source will then give you a reading of how bright the main source light is. Not the camera setting.

    Pointing the meter at the secondary light source, whether that's a reflector or a dark area that's "lighting" the dark side of the face, gives you reading on how bright it is on that side. Again this is not a camera setting. (This can also measure the difference between various studio lights.)

    The difference between these readings is the ratio of contrast. So if the light on the bright side is three stops brighter than the light on the dark side, the ratio is 3:1.

    With careful placement you can't get a high contrast (3:1) shot with details on both sides of the face.

    Those that recommend simply taking a meter reading pointed at the light source as the camera setting are making assumptions about what you want from your photo. Typically that type of reading will provide very little if any detail on the dark side of the face.

    Is that what you want?

    If not then you have to find a compromise that will get you what you want.

    That's not as hard as it may sound. If the lighting ratio is right (whether that's 2:1 or 3:1 or 1:1) then a normal (pointed at the camera incident reading) will get you in the ballpark for camera settings. The fine tuning is done when printing if you are using negative film. If you are using transparency film you will need to be more accurate on camera setting and that will come with experience and you will learn to judge the angle of the incident meter head to get what you want.
     
  8. wiltw

    wiltw Subscriber

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    Hey, you calling me inconsistent? :blink: :wink:

    1. When I shoot color neg, since it does not well tolerate underexposure, as that causes muddy color in the shadows: So I point my hemisphere at the lens, which biases my reading to factor in shadow areas.
    2. When I shoot color transparency (or digital), since that does not well tolerate overexposure, as that loses details in the highlights: So I point my hemisphere at the [edit: LIGHT], which biases my reading to prioritize the higher areas of illumination (and the belief that the shadows will 'take care of themselves' while I try to preserve my highlight detail.

    Most folks choose and use one technique and they don't really understand Why, or that there may be a better way under different circumstances...instead they think the other way is 'wrong'!
     
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  9. Poisson Du Jour

    Poisson Du Jour Member

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    I'm not saying it's 'wrong'. I'm saying that it does not make sense. :confused: :smile:

    I would not have any qualms using the memory function of most light meters: 1. highlight (illuminated); 2. shadow; 3. average both; 4. now adjust for high- or low-key. At the end of the day, whatever rows your boat, and experimentation and notetaking — yes, even if you waste a few 5x4 sheets.
     
  10. wiltw

    wiltw Subscriber

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    You have every right to be confused...I meant to say that I point the hemisphere at the LIGHT. I corrected my earlier post. Thanks for keeping me honest! :whistling:
     
  11. Lee L

    Lee L Member

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    As Brian Shaw mentions, the Dunn and Wakefield book is an excellent guide. Here is an excerpt on incident metering and the use of flat disc vs hemispherical (Norwood style) diffusers with incident meters. (The Exposure Manual, 4th edition, page 131, column 1)

    What's implied here is that the Duplex method is mainly for flat-receptor incident meters, and that domed incident meters compensate in the same way as the flat-receptor Duplex method until the light source is more than about 40 degrees behind the plane of the subject.

    Lee L
     
  12. markbarendt

    markbarendt Subscriber

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    I have the third edition of this book, and it is a really great reference.
     
  13. Lee L

    Lee L Member

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    I found my copy of Dunn and Wakefield on Abebooks for about US$4, including shipping. It was printed in the UK, and so appears to be more common there. Abebooks.com typically has dealers with copies of the 4th edition (1981) for around $5-$6 including shipping, even shipping from the UK to the US.

    Well worth the money.

    FWIW, I worked in perhaps a dozen professional studios in the 80's, and never saw anyone point an incident meter dome anywhere but at the camera lens from the subject position (or equivalent). Dean Collins advocated pointing at the key light (in artificially lit portraits on low contrast negative portrait films VPS and VPL) and was the first and only pro I knew of advising this. I think his popular portrait training videos were widely viewed and his unorthodox and special-case incident metering advice propagated on the internet and elsewhere by people who didn't have wider training or experience as the correct method for all situations.

    You can, of course, use any light meter in any way that works for you, but the design of the hemispheric receptor incident meter is made to replicate a three dimensional object as seen by the camera, which means pointing the meter at the camera from the subject position (or in the same direction, i.e. parallel to that line, in the same light).

    Lee