Barrell Distortion (London Bridge is Falling Down!)

Discussion in 'Beyond the Basics' started by Vautrin, Dec 26, 2009.

  1. Vautrin

    Vautrin No longer a newbie, moving up!

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    So I was in London recently and had a chance to try out a wide angle lens I had just bought. And the pictures came out nice, but they're a little tilted:

    [​IMG]

    When I took that picture London bridge was straight ahead, and I was using a tripod that had been leveled.

    So I guess this is barrel distortion? I was wondering if anyone had any thoughts on how to minimize it, and how to recover any shots like this (I tried straightening them but the perspective is still off)

    Thanks ahead of time for any c&c!

    Dan
     
  2. Garbz

    Garbz No longer a newbie, moving up!

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    This isn't barrel distortion, this is perspective distortion resulting from using a wide angle lens pointed upwards. This causes straight edges to converge at a point, i.e. the line down the middle of the frame is straight, but those starting left and right at the bottom converge to a point at the top.

    The only way around this is to shoo from further away with a longer focal length, or using a tilt-shift camera which allows the focal plane angle to be adjusted.
     
  3. JSD

    JSD TPF Noob!

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    Not to be too anal but this is not London Bridge, it's Tower Bridge. London Bridge is in Arizona now. The joke in England is: "did the Yanks think they were buying Tower Bridge?"
     
  4. Dwig

    Dwig TPF Noob!

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    Its a real effect that results from the plane of the subject and the plane of the sensor not being parallel and it not actually a form of "distortion".

    It doesn't have anything to do with the lens, at least directly. It happens regardless of the focal length of the lens. It is just typically more pronounced in wide angle shots since many WA shots are done in tight situations that call for increases camera tilt.

    It can be corrected by either taking care that the camera's sensor/film plane if exactly vertical, using either a shift lens or cropping to center the desired image, or by transforms (Photoshop term; may vary in other image editors) in post processing.
     
  5. KmH

    KmH Helping photographers learn to fish Supporting Member

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    Many times this can be fixed rather easily using Photoshop's crop tool. There are a number of online tutorials.
     

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