How to Spot Meter for Portraits

Discussion in 'Beginner Questions' started by brandy_kimble, Dec 16, 2013.

  1. Hi!
    I am a newborn photographer and most of my images are taken indoors with soft natural window light.

    I wanted to know how spot metering works and how to use it?
    Thank you!
     
  2. Brandy, a spot meter reads light only from a small, defined area. It has a narrow field. In general, several readings are taken and then combined (a "weighted average"). For portrait work you will probably be better off with an incident light meter. If you have only the spot meter, place a piece of white card or paper in the same light as your subject, take a reading off that, and open up the lens two and a half stops more than the indicated value (or adjust shutter speed to get the same exposure). Film speed must be set on the meter beforehand.
     
  3. In camera spot metering can be used for measuring a person/face when you have a brightly lit background. Mostly the viewfinder has an indication of the part of the scene that is measured. So you can measure the face and give that the proper exposure. Very likely the background will be over/underexposed but the spot metering technique works well.
     
  4. I'd just like to say you write very well for a newborn ;).
     
  5. david_henderson

    david_henderson www.photography001.com

    The thing to remember about spot metering is that if you set on the camera (or allow the camera to set, depending on whether your meter is in-camera or separate) the same value that your spotmeter records for a particular place , then that place will be rendered as a mid-tone. So spot metering is not just a case of pointing the meter at one small area , taking a reading and setting the camera at that exposure. You always have to think about how you want various parts of your subject rendered- whether at mid-tone or a stop (or two) lighter or darker. Thats why the first respondent said that in general several readings are taken, and you decide -or calculate- the exposure based on what gives you the best fit with how you see the picture.
    Spot metering can be an extremely accurate way of controlling exposure, so the photographer understands how the brightest and the darkest parts of the scene will be rendered. But there's a learning curve involved, and you will make mistakes while you're on it. If you're metering with a handheld meter, I'd also suggest that incident metering may be easier for you. Otherwise matrix or similar and bracket.
     
  6. Well you've been given some good tips. The only one I'd add is to use your camera's spot meter and set your camera's
    exposure biasing for +1.0 if you are reading the baby's face. If the baby is dark skin and the overall contrast (the range
    from highlighlights to shadows in the scene isn't great keep biasing at normal.

    Do you have a WhiBal target? If so , use it.



    Also shoot raw.


    Finally: play.
     
  7. James G. Dainis

    James G. Dainis Moderator

    Spot meter a white piece of paper and take a photo of it using the indicated exposure. You will get a photo of a gray piece of paper.

    Spot meter a black piece of paper and take a photo of it using the indicated exposure. You will get a photo of a gray piece of paper.

    Now you know how a spot meter works. It will try to set an exposure to render a middle gray, Zone 5, result. A spot meter does not give you the correct exposure unless the subject is already a middle gray. You have to learn how to adjust from the indicated middle gray exposure to the correct exposure for the subject. Generally, that would mean take a spot meter reading of the person's face and open up one stop or, as Ellis said, have the camera biased for +1.0.
     
  8. Congratulations on wanting to use spot metering. It will allow you to control the camera, not vice versa. But like many good things in life, it will take some work.
    As others have suggested, after spot metering a tiny area (on my dSLR a 3mm or 0.12" circle, really tiny), you will need to determine if biasing is necessary. Take this photo of yours as an example.
    http://www.photo.net/photo/16781853
    If you spot meter on her chest under her chin, there is little need to bias since that spot is close to 18% gray. But if you spot meter on her shiny cheek, you will need to bias by overexposing one stop or so.
    Spot metering on a dSLR poses another challenge. On a dSLR the focus point and exposure point are tied together in the default settings. In your photo, the critical focus point is obviously the eyes, but that's not where you would want to spot meter. OTOH, if you spot meter on the cheek or on the chest, you would be focusing there as well, which is not the critical focus point.
    One way to disengage the focus point from the exposure point on a dSLR is using Back Button Focusing. That will allow you to focus on an eye and lock the focus, and then spot meter on the chin or the chest.
    http://www.photo.net/casual-conversations-forum/00c8ZZ
     
  9. Just to add to what Robert said, an alternative is to spot meter on an area that you'd consider 18% gray (it doesn't actually have to be gray though), and use the AEL button on your camera to lock the exposure. You might have to check your camera settings to determine how long the lock will hold. Another option is to spot meter, then put your camera on full manual mode and set the shutter speed and aperture to match the readings that correspond to the spot metering. So many options, so little time...
     
  10. As long as you recall that what you are metering from will be rendered as a mid-tone, you will get the hang of it if you practice metering off different parts of the face in different lighting. Elli's suggestion works well for Causcasian faces that are not in shadow. I spent years metering off the palm of my hand and opening up one stop when I had a Canon FTb, which had no automatic anything and only a spot meter.
     
  11. Thank you all for the answers! Each answer has helped a ton! I practiced spot metering today on a darker toned person and realized when I spot metered on his face and under exposed it by two notches the exposure was perfect! So I will be playing around with it, and hopefully get the hang of it.
    Also, is there a big difference between spot metering and matrix metering? Is one better than the other when it comes to indoor portraits?
     
  12. There are two things that you need to know.
    The first is the obvious thing. You point your spot meter at an area in the scene, and it meters that area.
    The tricky thing is that a spot meter is tuned to a certain level of brightness (called reflectance, but you can think of it as brightness). This is about the brightness of Royal Blue.
    If the area that you are metering is about the same brightness as Royal Blue, you probably won't have to make any adjustments. But if it's darker, like Navy Blue, or lighter, like Sky Blue, your meter reading won't give you the results that you expect. You might have to make an adjustment to make the whole image darker (in case you meter a dark area of the scene) or lighter in case you meter something brighter.
    One way to adjust to make the image lighter is to add more time to the shutter speed (smaller number). Another way is to use positive (+1) exposure compensation.
    One way to adjust to make the image darker is to shorten the time of the shutter speed (higher number). Another ways is to use negative (-1) exposure compensation.
    If you meter white clothing, you'll need to increase the amount of light that the meter asks for by about four times (doubled, and then doubled again).
    If you meter the skin of a fair complected person or something light in color such as vivid yellow or baby blue, double the amount of light that the meter asks for.
    If you meter Royal Blue, Emerald Green, Scarlet Red, or medium gray, no adjustment will be necessary.
    If you meter Forest Green, reduce the amount of time by half.
    If you meter Navy Blue, you might need to cut the amount of time by as much as a fourth.
     
  13. Just to add another option, there is generally a choice of 'center-weighted' metering as well, which meters more heavily on a smaller portion of the frame, so you might want to try that and compare results. Simple to do, of course, in the digital world.
     
  14. As has been said above, spot metering on a non 18% gray requires compensating for the difference between the tone of what you are metering and 18%. Since I don't see in shades of gray I wondered what colors are 18% and found that answer in a Rocky Mountain training class. 18%: coco cola red, school bus yellow, electric cord orange, blue north sky. Spot on those and zero out your meter. And one stop brighter are pastels.
     
  15. Add most green foliage to the list of commonly available surfaces that most reflective meters see as pretty close to 18% gray. But it's generally better to use an averaging meter than spot, to even out the effects of bright reflections and shadow.
     

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