Fast Shutter Speed=Dark Image

Discussion in 'Sports' started by glenn_carroll, Aug 17, 2008.

  1. Hello all

    I have a EOS XSi, and a 24-105mm f/4L lens. I want to take a picture of a dog jumping in the air, or just freeze
    motion in general. I would assume this lens is capable of taking fast pictures, even though the aperture is not
    great. To test the abilities of the lens, I simply went outside to take pictures of a still object such as a
    parked car in broad daylight with a fast shutter speed. The picture is black. I then adjust the aperture to
    wide open at 4, and the picture is still quite dark at 1/500.

    Mark Davey posted a helpful image at the bottom of this page: http://www.photo.net/learn/sports/overview
    It shows boys playing soccer. Motion was nearly frozen at f/4 with 1/500 of a second.

    I want a crisp photo of a dog catching a ball in mid air on a gorgeous sunny day with lush green grass and
    flowers in the background (haha). What am i doing wrong? thnx

    Glenn
     
  2. You are letting the light meter make all the decisions on your exposure when you should be making them. The light meter is looking for exposure based on 18% gray. If you are shooting a scene that is mostly light in nature and you do not compensate for that you photo will turn out mostly dull and gray. The same applies if the scene is mostly dark as well. Your equipment will work well for what you want to shoot. Adjust you exposure compensation on your camera up or down to get the shoot your looking for to bracket you shot. Or you could take a meter reading on your main subject up close than lock that reading in to take the shot. That will mainly apply if the lighting you are in is constant such as a sunny day. Hope this points you in the right direction and good luck!
     
  3. Thanks Bruce....so if I am trying to take a picture of something moving fast, I have to always increase the exposure comp. to make up for extremely fast shutter speeds. Can adjusting ISO do anything to improve picture quality in these circumstances?
     
  4. Glenn if you want to freeze the action you definitely need a fast shutter speed. Depending on the light increasing the ISO will allow you to increase your shutter speed. However you should still bracket your exposure to get the shot you want.
     
  5. Try tgis- set your camera on the 'Sports" auto setting and take a shot. Then look at the info for that image, gining you the ISO, shotter spd and aperture used to get that image.If you need faster shutter, then one of the ofher two have to change as well to get a similarly eposed image.

    I'm thinking your ISO may have been set too low, 1/500 at f4 should give you good action capture in normal daylight.
     
  6. William Michael

    William Michael Moderator Staff Member

    > I want a crisp photo of a dog catching a ball in mid air on a gorgeous sunny day with lush green grass and flowers
    in the background (haha) <

    If the puppy is front lit with good sunlight, try: 1/500s @ F16 @ ISO 400

    Though 1/1000s @ F16 @ ISO800, or 1/1000s @F11 @ ISO400 might be better.

    That is an example of the ``f16 rule`` for front lit, average subjects, in full sun.

    It is useful to know this rule and the variants of it: for when your light meter goes belly up. **


    ***


    It might be better to use you light meter though.

    I think you might not fully understand the three elements of exposure: ISO; Shutter Speed; and Aperture? Please
    excuse if you do:

    The point is, the ``more sensitive`` to light you make your camera, by INCREASING the ISO, the relative LESS light
    you need to expose any particular scene: Less light to expose the scene can be accomplished with less time the
    sensor is exposed (faster shutter speed) or making the size of the funnel we let the light through, smaller (a smaller
    aperture).

    So careful selection of ISO, (and the use of fast lenses) are very important to sports photographers because both
    ALLOW the use of fast shutter speeds.

    ***

    Back to your puppy and your camera.

    No matter what lighting conditions you have, provided the dog stays in those lighting conditions (e.g. does not
    wander off into shade or the clouds do not move across the sun, for example), a basic MANUAL method to take this
    picture:

    Select M (manual mode)

    Fill the viewfinder frame of the camera with the dog, ensuring you do not cast your own shadow on him.

    Adjust the ISO and Aperture for a correct exposure, so that you have about F8 (if possible) and you keep the shutter
    speed at 1/500s.

    Have a play with the combinations possible for the light you have, and you most likely will understand better how the
    three exposure parameters interrelate.

    WW


    ** Please note that the f16 rule indicates ISO500 for this particular shot, but ISO400 was chosen in the example, for
    simplicity.

    The slight difference in the ISO (between 400 and 500) is of little consequence, as the ``f16 rule`` is only a guide, but
    a very good, and quite accurate guide, nonetheless.
     
  7. Dogs can vary greatly in how the camera metering responds: a black Flatcoat Retriever will probably cause the camera to suggest/select much too great an exposure, whereas a white Samoyed may be severely underexposed. That is why it is often best to photograph dogs using the M exposure mode on your camera - you control the exposure the camera uses. Methodology: with the sun behind you, fill the frame with the lush green grass (which acts as a good mid tone metering target) and set the aperture to f/4 in M mode. Now adjust the shutter speed until the metering is correct. If the shutter speed is too slow, then increase the ISO (double the value) and re-meter to check you are setting the correct higher shutter speed - repeat as necessary as light levels drop particularly towards sunset. Don't worry if your shutter speed is somewhat higher than 1/500th - in fact, you'll find that you need as fast as you can manage if you want detail of the dog's coat to be frozen if it is on the run. You should also make sure that the focus mode is set to AI Servo, and you should track the dog with the shutter release at half press for a second before starting to shoot - take several shots in continuous mode.
    00QXo5-65079584.jpg
     
  8. William Michael

    William Michael Moderator Staff Member

    ``Dogs can vary greatly in how the camera metering responds: a black Flatcoat Retriever will probably cause the camera to suggest/select much too great an exposure, whereas a white Samoyed may be severely underexposed.`` (MU)

    Yes.

    And that should be noted is where my ``basic MANUAL method to take this picture`` can come unhinged.

    Taking a meter reading from the dog, as I suggested, assumes the dog`s coat is a reasonable mid tone, (not matt black or white-white), which I did not stipulate.

    I was taking a very simple approach, to meter the subject in the lighting conditions that you were to shoot. I was keeping everything in one box, so to speak: and Mark`s answer highlights potential shortcomings of this method (at least I could have been explained it better for black and white dogs).

    Using the green grass as a midtone can be used to take a reading for the shot in open shade too: provided you meter the area of green grass which is in the same, open shade conditions, which will be lighting the dog.

    WW
     
  9. Thank you all for the responses. I need to read up a little more on the use of light meters. Are there any really good book recommendations on exposure? Thanks again
     
  10. Try "Understanding Exposure" by Bryan Peterson.
     
  11. Well...what do you know? It seems like Photonet has persuaded Bryan to serialise some of the key content, starting with this new article:

    http://www.photo.net/learn/basic-photo-tips/aperture-shutterspeed-iso/
     

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