Automatic Matrix/Spot Metering and low lighting

Discussion in 'Photography' started by D.R, Apr 13, 2004.

  1. D.R

    D.R Guest

    Hi there.

    When in a dark situation, and I stick the Nikon F80 onto auto (any mode),
    will the automatic metering attempt to capture the picture as I see it (very
    dark) or will it try to lighten it up to daylight? I would think that it tries to
    capture as I see it, and I would have to manually over expose to lighten it
    up - however, the result is not always so. I have had mixed results and
    am trying to figure it out so I can learn how to compensate. I have taken
    photos on auto at dusk that came out like daytime, and others that came
    out dark.

    If I am in low light room, do I over expose by one or two stops over and
    above the metered readings to bring out the detail (without flash)?

    Is there a rough guide anywhere that lists the times of day, and weather
    conditions, etc and approximate ballpark aperture and shutter speeds.
    I guess as the years go by I will soon recognize by trial and error, but
    would like a guide to know if something (eg a white object) is confusing
    my metering.

    Thanks in advance.
    D.R, Apr 13, 2004
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  2. Okay, you asked a lot of questions, but I'll try to answer some. With the
    camera set on automatic, meters coupled to the camera's exposure controls
    (shutter speed and aperture) will always try to give correct daylight-like
    exposure. So, the camera will try to lighten a dark scene (dark compared to
    daylight) or darken a lighter scene (lighter compared to daylight). To
    eliminate this automatic exposure adjustment, the camera can be set on
    manual (or shutter/aperture priority). The meter will still read the scene
    to give daylight-like results on film, but you can set the exposure controls
    manually to give whatever results you want. For example, if you want the
    scene to remain dark, you can set the shutter speed faster (a higher number)
    than the number recommended by the meter and set the aperture as
    recommended. Or you can set the aperture to a number higher than recommended
    by the meter and use the recommended shutter speed. Both of these last two
    sentences will give a darker image on film. To get a lighter image, either
    use a slower shutter speed or a smaller aperture. If you don't understand
    this, get a book and carefully read about metering and exposure.

    Meters are not perfect and can be easily fooled by unusual scenes. For
    example, if you're photographing a normally lighted person against a fairly
    dark background, the meter may be fooled by the dark background if the
    subject does not cover a large enough area of the photograph being taken.
    When this happens, the person may be too light on the final image and the
    dark background closer to normal daylight. The key is getting a good meter
    reading of the main subject. You can do this by using the spotmeter mode,
    pointing the meter directly at your main subject, locking the exposure
    (often done by pressing the shutter release button half way down),
    recomposing your image to place the subject where you want, and then taking
    the picure (finish pressing the shutter release button). There are several
    other ways, so again read about metering and exposure.

    Explained in the first paragraph.

    Not really. I have see something like this, but it would be greatly
    inaccurate since this varies based on film speed, lens speed, filters used,
    and other factors. The best tool is your camera's meter. Read the owners
    manual about metering and exposure. Search web sites and read about this.
    Study each picture to see what went wrong, how to correct it, and remember
    this for future similar situations. These are skills you will use as long as
    you're taking picures, so make the effort to learn it now.

    Dwight Stewart
    Dwight Stewart, Apr 13, 2004
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  3. D.R

    D.R Guest

    Hi Dwight,

    Thanks for the reply! :)

    Cool, so basically the metering will try to lighten to daylight.
    Great, now I know which direction I need to compensate the exposure.
    I normally use shutter priority and spot metering, but have had
    a go with the matrix and center weighed metering modes - however,
    using Matrix metering resulted in most of a roll of film being
    under-exposed. The manual pretty much said that this mode is a no-
    brainer. I lesson I probably won't forget.
    I will revert to using spot metering now. I have
    read much about using grey cards to proper exposure.
    Are these the usual tool of the trade, and would
    a camera shop sell one?

    I should also write down the settings of each frame
    in a notebook or something.
    Spot metering... got it. :)

    So if I want the scene to look as I see it, then
    I have to compensate (guess or calculate) for this.
    ie. want night-time to look like night-time.

    In wonder why cameras don't have a "as I see it"
    mode, and a separate "lighten/darken to daylight"
    mode. ;-)
    I have had one weird photo come out. It was
    taken indoors on a rainy day. Lighting was
    dim. The photo had black background but
    reasonably exposed subject (under exposed
    (really dark) around the outside of silohette).
    The photo did not look dull grey like many
    under exposed photos. Color of subject was ok.
    The effect looked really cool, and I have no
    idea what happened. Looked like I had done it
    on purpose though. :)

    Thanks again.
    D.R, Apr 13, 2004
  4. D.R

    JME Guest

    JME, Apr 14, 2004
  5. D.R

    D.R Guest

    Thanks for the link. Very interesting.

    Also found the following helpful:

    "If the "sunny f/16 rule" sounds familiar, the exposure setting
    used follows it. The "sunny f/16" rule states that a good
    exposure can be made on a sunny day with clear sky using an
    aperture of f/16 and a shutter speed of 1/(ISO film speed)."

    and of course the table near the bottom.

    Thanks. :)
    D.R, Apr 14, 2004

  6. The camera will use the meter's readings to try to adjust the camera
    settings to give daylight-like results on the final image.

    I forgot to mention this in the first message. You can also use the full
    auto mode and adjust the exposure using the exposure compensation setting.
    Again, if you meter properly (meter the subject), the camera will usually
    give good results. You only need to compensate when you want something other
    than daylight-like results (you want the image to stay light or dark) or you
    think the meter is being fooled by an unusual scene (a mostly dark or mostly
    light scene).

    Not really. There are several tricks you can use instead. These cards are
    16-18% grey, which is somewhere between a normal white person's skin tone
    (especially with a tan) and the color red. In fact, 16-18% grey is the color
    red on a sunny day on B&W film (a light meter doesn't see color, only
    light). So, you will get accurate enough results by metering your own hand,
    a subject's face, or a nearby red object. About the only time I use a grey
    card is when I shoot an unusual scene on print film. To get accurate results
    from the processing lab, I'll shoot a grey card first (in the same light as
    my intended image) and then tell the processor to process the roll using the
    settings obtained from the frame with the grey card. Most camera shops
    should have a grey card available (or can order one).

    Because your eyes are so much more complex than a camera. Each eye
    contains an iris which constantly adjusts the brightness of the images you
    see, allowing in more light when it's dark and less when it's very bright.
    It can even adjust for very small changes in light and for fairly small
    sources of light. Your eye can even select what to adjust for (something in
    a shadow on a bright sunny day, for example) A camera couldn't possibly keep
    up with all this. The closest it can come to this is the full auto mode.

    That's caused by light fall-off. As light travels further from a source,
    it spreads and is therefore weaker in any one spot. Hence, if you have a
    relatively small nearby light source (a window, flash unit, studio light, or
    similar) in front of a subject and expose for that subject, the light behind
    the subject will grow darker as it travels further away (your complex eyes
    will adjust for this but film won't). If there is nothing behind the subject
    for some distance, the background in the final image will eventually be very
    dark or even completely black. You might wonder why this isn't so with the
    sun. While the sun is a small light source, it is not nearby (the subject
    and background is virtually the same relative distance from the sun).

    Dwight Stewart
    Dwight Stewart, Apr 14, 2004
  7. D.R

    D.R Guest

    Thanks for the reply!

    I have taken some photos at night-time using
    aperture priority mode. Scene came out as dark
    as I saw it using the cameras settings. Nighttime
    sky with reflection of river. I guess I should
    have written down where I metered and the settings.

    Full auto mode usually ends up with a shutter speed
    I cannot use as my hands are not steady enough. Often
    it's 1/60.
    Makes perfect sense. So a grey card is needed only if
    there is nothing to meter from, eg a snow scene?

    Would using the flash indoors on a grey day do this?
    The camera would be exposing knowing that flash is
    being used.

    Just another question. When using the F80 (N80) with
    the SB24 in TTL mode, in daylight on any of the priority
    modes, would that fill-flash automatically, or do I need
    to do manual adjustments? I read somewhere about setting
    the film ISO on the flash, not the camera, to a higher
    speed to achieve this. Or is this only for manual flash?

    I recall also that with the SB24, that spot metering mode
    is not possible. Would I spot meter, and then stick it
    onto manual to get around this? I have the SB24 user manual,
    but it doesn't seem real clear.

    Thanks again! :)
    D.R, Apr 14, 2004

  8. Absolutely. How dark your background will be depends on how far behind the
    subject, how strong your flash is (how much light it can throw onto that
    background), and your camera settings at the moment.

    Sorry, you'd have to ask Nikon, or another Nikon F80 user, for specific
    information about fill-flash with that camera. While I can answer your
    general questions about light, flash, meters, and so on, I'm not familiar
    with that specific camera (I use a Minolta Maxxum 7).

    Dwight Stewart
    Dwight Stewart, Apr 15, 2004
  9. Larry CdeBaca, Apr 16, 2004
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