Canon 10-22, some questions

Discussion in 'Canon' started by jazu, May 8, 2008.

  1. jazu

    jazu Guest

    Hi
    I just got my Canon 10-22
    When switch is on AF I'm able to turn manually focusing ring. Is that as it
    should be ?
    In my other 2 lenses this is impossible.
    Please look at this pic
    http://www.flickr.com/photos/[email protected]/2475419334/
    These distortion scares me a lot.
    Can distortion level varies between lenses of the same model? Should I
    change mine?
    On weekend I will do direct competition between Sigma 18-200 and Canon 10-22
    thnx

    I believe, I'll back with more questions:)
     
    jazu, May 8, 2008
    #1
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  2. jazu

    Troy Piggins Guest

    Yes. That's normal for that lens.
    What are they?
    Don't be scared. It's just a photo. :)
    That distortion is a function of the focal length IIUC - 10mm
    focal length gives that fisheye look. I think it is less
    dramatic after 16mm or so.

    You can use it for some really cool effects/photos.
    How can you fairly compare a 18-200mm lens and a 10-22mm lens?
    They are completely different, and the only possible comparison
    could be made in the 18-22mm focal range.
    :)
     
    Troy Piggins, May 8, 2008
    #2
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  3. jazu

    jazu Guest

    I'm aware of that. The competition will in 18-22 range
     
    jazu, May 8, 2008
    #3
  4. jazu

    Paul Furman Guest

    I predict you will kick the 18-200's ass.

    :)

    Or at least somewhat better.

    --
    Paul Furman
    www.edgehill.net
    www.baynatives.com

    all google groups messages filtered due to spam
     
    Paul Furman, May 8, 2008
    #4
  5. jazu

    jazu Guest

    My reason to buy this lens was to make picture similar to this:
    http://www.vopenhouse.ca/video/2738_helmcken/Gallery/
    I was amazed how these pic are wide and how these vertical line are so
    straigth in the picture. After playing with my new 10-22 lens I came to
    conclusion that these pic must be shot exactly from half heigh of the
    ceiling. I start to think about it and I found the way how any can find out
    how any lens could distord picture. Just to keep in right side of viewfinder
    some naturaly vertical line and next tilt camera up and down. Haha I don't
    think I'm discoverig America here. I just found this way on my own and I
    believe all photographers know it. Logic tells me that (unless they don't
    know it:)
     
    jazu, May 8, 2008
    #5
  6. jazu

    frederick Guest

    Download "PTLens" and pay $15 to register after 10 shot trial has
    expired. Use it to correct barrel, pincushion, or complex pattern lens
    distortions simply and very effectively.
    If you don't have Photoshop, download the Gimp (freeware). Set default
    interpolation method to Lanczos. Use the perspective correction tool to
    correct perspective distortion - and note that "some" correction rather
    than 100% correction might give the result that you need WRT buildings
    leaning backwards etc. Perfect correction tends to give a "surreal"
    effect in some cases, and may not be what you want. Set the tool to
    display preview until you get the hang of using it.
    PTLens is easy to use. Gimp is more complex, but better than Photoshop
    for that job, and no more difficult to use.
     
    frederick, May 8, 2008
    #6
  7. jazu

    Focus Guest

    Agreed. PTlens is the tool for the job and 15.- is not worth mentioning ;-)
    You don't need PS for PTlens, but it works with PS also.
     
    Focus, May 8, 2008
    #7
  8. FTM.
    It's not a bug ...
    .... it's a feature every good lens has or should have.
    That happens with *any* lens, no matter how perfect, that you
    tilt up that much. That's simply geometry.[1]

    However, since longer lenses don't record the borders and tele
    lenses only the very centre, the effect will not be as
    drastic.

    -Wolfgang

    [1] You can counter that effect by bringing the film plane to
    be parallel to your objects, which usually means vertical.
    That means either using a tiltable lens[2] or not tilting the
    lens at all (ultra-wide angle really is sensitive there) ...
    Within limits and with limitations you can post-process
    such images to reduce or eliminate the distortion.

    [2] large format and some medium format cameras allow that,
    and there are also a very few shift- and tiltable lenses
    available for 35mm format, but none so wide.
     
    Wolfgang Weisselberg, May 8, 2008
    #8
  9. I've been reading comments about the inadvisability of doing much of
    that kind of software correction for some time. So I was very
    surprised to discover just how well PTLens does it, and how very
    little detail gets lost.

    Here is an example of keeping the camera level in portrait mode and
    using wide angle to get in the top of a tall building, then using
    PTLens to get rid of slight tilt, vertical divergence, barrel
    distortion, and chromatic aberration, and then cropping the bottom
    off. The corrected image also has links in its description to highly
    magnified portions of the before and after images to see how little
    detail was lost.

    Original image:
    http://www.flickr.com/photos/chris_malcolm/2475841383/

    Edited (mostly PTLens):
    http://www.flickr.com/photos/chris_malcolm/2409634595/

    Here is an example of more extreme barrel distortion corrected by
    PTLens, an automatic one-click operation because it has the geometric
    distortion factors for that lens in its database and got the zoomed
    focal length from the EXIF data.

    Original image with barrel distortion in foreground balustrade:
    http://www.flickr.com/photos/chris_malcolm/476846534/

    Barrel distortion removed by PTLens:
    http://www.flickr.com/photos/chris_malcolm/2409633975/

    Finally here is an example of more extreme perspective correction.

    Original tilted back image:
    http://www.flickr.com/photos/chris_malcolm/2475970067/

    Perspective corrected by PTLens:
    http://www.flickr.com/photos/chris_malcolm/2440152150/
     
    Chris Malcolm, May 8, 2008
    #9
  10. jazu

    Paul Furman Guest

    Look at 07 and you'll see some very noticeable barrel distortion.

    --
    Paul Furman
    www.edgehill.net
    www.baynatives.com

    all google groups messages filtered due to spam
     
    Paul Furman, May 8, 2008
    #10
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