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Sports shots with fast telephoto

ruttrutt Registered Users Posts: 6,511 Major grins
edited March 12, 2004 in Technique
Over the last couple of years I've taken lots of cross country skiing photos with my 80-200 L 2.8. I like close cropped shots and I like to have the background blurred to center attention on the participants. I use a 10D, so the lens is really 300mm equivalent.

What I want are shots like this:

2755566-M.jpg

But all to often I get shots like this:

2757164-M.jpg

The difference is that focus in the first picture is good if a little soft, but in the second picture, focus seems to be sharper on the bib than on the face, where I think it's unacceptable for printing at any large size. I'd like to understand the cause of this and figure out how to improve.

So here are my specific questions:
  1. I know that telephotos have less depth of field than wider lenses. If I use a 200mm lens on a 10D, will it have the depth of field of a 300mm lens? Or will it behave in this respect like a 200mm?
  2. By opening up the lens all the way, I am able to shoot at a very fast shutter speed. Both of these shots are faster than 1/500th. Is that fast enough to handhold this lens? It does have IS. How fast would the shutter have to be to make this work?
  3. Catching the action in these events is hard and requires taking a lot of shots fast. My goal (perhaps unachievable) is to take a good shot of each participant. So I set the camera's drive for multiple shots and use "AI Server" autofocus mode. One problem with this is I don't know which focus point it's using and I don't really understand what it's doing. My batting average is better than with one-shot focus. Does anybody understand this better?
  4. Perhaps I need to back off on the aperture somewhat in order to increase the depth of field. But I still want the background out of focus. Does anyone have any specific advice here?
If not now, when?

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    Shay StephensShay Stephens Registered Users Posts: 3,165 Major grins
    edited March 11, 2004
    So here are my specific questions:
    1. I know that telephotos have less depth of field than wider lenses. If I use a 200mm lens on a 10D, will it have the depth of field of a 300mm lens? Or will it behave in this respect like a 200mm?
    No, only the field of view would be the same as a 320mm lens, but the DOF remains the same as a 200mm lens since the optics producing the DOF are indeed 200mm. The 1.6 FOV crop only applies to the field of view because the sensor is smaller than 35mm film, so the image circle put down by the lens is not fully utilized by the sensor and the portion that is wasted is within the FOV crop area, the area that 35mm film would occupy.
    1. By opening up the lens all the way, I am able to shoot at a very fast shutter speed. Both of these shots are faster than 1/500th. Is that fast enough to handhold this lens? It does have IS. How fast would the shutter have to be to make this work?
    The general rule of thumb is to have the shutter speed at least as fast as the focal length. So if you are zoomed in all the way at 200mm, you wold want a shutter speed of at least 1/200. IS and tripods and other things allow this shutter speed to be slower.
    1. Catching the action in these events is hard and requires taking a lot of shots fast. My goal (perhaps unachievable) is to take a good shot of each participant. So I set the camera's drive for multiple shots and use "AI Server" autofocus mode. One problem with this is I don't know which focus point it's using and I don't really understand what it's doing. My batting average is better than with one-shot focus. Does anybody understand this better?
    Action shots are hard. The more you do it, the better you will become at it. But there are no magic bullets.
    1. Perhaps I need to back off on the aperture somewhat in order to increase the depth of field. But I still want the background out of focus. Does anyone have any specific advice here?
    If you use a smaller aperture, you will get more DOF, but the background will becom more and more in focus. You may be able to find a happy medium, but I doubt you can change it too much. You may want to consider manually focusing on the area you expect the skier to be, make the aperture small enough to capture this area in sharp focus but wide enough to throw the background out of focus enough for your taste, and then fire away when they are in the focus zone.
    Creator of Dgrin's "Last Photographer Standing" contest
    "Failure is feedback. And feedback is the breakfast of champions." - fortune cookie
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    DoctorItDoctorIt Administrators Posts: 11,951 moderator
    edited March 12, 2004
    BKYSL - Bill Koch Youth Ski League, right?
    Brings back memories...

    :D
    Erik
    moderator of: The Flea Market [ guidelines ]


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    cletuscletus Registered Users Posts: 1,930 Major grins
    edited March 12, 2004
    Shay already addressed most of your questions, but I wanted to add a couple things.

    When I was shooting sports for the school newspaper I wanted the exact look you're going for. The key to getting that look was using a shutter speed of 1/500th of a second or better. For a human subject, 1/500th is going to freeze any motion. The other benefit of a 1/500th shutter speed, is that camera shake is not going to be an issue.

    The next issue is controlling the depth of field. I think that you'll find that by stopping down to f4 or so will give you just a little bit more depth of field. The background will still be out of focus, but the exact focus point wont be as critical.

    Here a couple strategies I might try:
    1. Try some shots with the camera setup for shutter priority at 1/500th. If the background isn't soft enough, try upping the shutter speed a bit.
    2. Put the camera in aperture priority and try several apertures to find the one that just gives you the nice soft background you're looking for. Hopefully the aperture you pick wont be wide open and you'll have a bit more depth of field to play with.
    Hope this helps,

    -Eric
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    soupsoup Registered Users Posts: 78 Big grins
    edited March 12, 2004
    panning the action will throw the BG out of focus - in an action type of way -with just about any aperture setting, but 1/500th might be too quick to get a good pan effect...


    i dont trust the auto focus tracking much, and tend to manually focus most of the time - although i don't shoot alot of sporting events, i look for flying birds quite a bit
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    ruttrutt Registered Users Posts: 6,511 Major grins
    edited March 12, 2004
    DoctorIt wrote:
    BKYSL - Bill Koch Youth Ski League, right?
    Brings back memories...

    :D
    Yes, exactly. This year was in Waterville Vally, NH and it was pretty soggy.

    If you are interested, take a look at all my shots of BKL activities here. If you are a real New England XC racing old timer, then this should really bring back the memories:

    91672-M-1.jpg

    Bob Gray and Mike Gallagher, both 3 time Olympains at the 2003 Bill Koch Festival in Putney, VT
    If not now, when?
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