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Thread: Rotating lens panoramics and field curvature

  1. #1

    Rotating lens panoramics and field curvature

    I'm a relative newcomer to ULF and have launched my 7x17 project.

    However, ever since I saw Jeff Bridges demo his 35mm Widelux on a recent episode of the television program, "Sunday Morning," I've found myself quite curious. Am I understanding all this correctly?

    A rotating lens panoramic camera, like Widelux, Noblex, or Cirkut (??) inherently seems to produce field curvature. I find this objectionable. But I understand, I think, that depending on the nature of the subject and it's distance from camera obvious curvature can be avoided to a great extent. Is this basically correct?

    Secondly, looks like a camera like the Fuji GX-617, with stationary but (by choosing a) very wide lens, avoids the field curvature problem (but, of course, not the natural distortions inherent in using an extreme wide angle lens). That "natural" distortion, for me, is far more tolerable than the obvious field curvature produced by a lens that moves.

    What do you folks who like these cameras most like about them? Fixed or rotating lens? Do you like the look of the field curvature, or do you avoid it? The extreme portability and relative ease of operation seems attractive. Plus, in 35 mm color format, film is obviously (even in 120) simple to get and process (by lab). How about printing? Any hassles there? I assume you need custom lab work. How big do you like to print? Do the built in lenses of the Noblex and Widelux, for example, produce images sharp enough to enlarge to decent size?

    Well, you can tell I'm very curious. Anyone who would be willing to further my education a little will be very much appreciated! Thank you, thank you!

  2. #2

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    Rotating lens panoramics and field curvature



    Neither the rectilinear perspective of a traditional lens or the cylindrical perspective of a swing lens camera is really 'natural' or more correct. Like different world map projections, they're just different compromises.



    For wild landscapes I think cylindrical perspective is often more natural-looking than rectilinear. For instance, when photographing the surrounding peaks from a mountaintop. I don't have a swing-lens camera but I get the same effect with stitched panoramas. I've done several mountaintop views this way, and nobody ever thinks they look distorted.


  3. #3
    tim atherton's Avatar
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    Rotating lens panoramics and field curvature

    hunt down the work of Geoffrey James.

    imo the majority of his rotating lens panoramic landscapes and cityscapes that I've seen rarely display the field curvature you describe - at least not in a way that is objectionable. He is a master at dealing with scenes with a lot of middle and foreground (as well as distant background) and yet not allowing the distortion to be an overwhelming factor. Not many seem able to do this well

    His recent Toronto work, his Italian Gardens book, the Campagna Romana book and (I think?) some of the Olmsted book photographs for instance

    I had been put off by the obvious "banana" look of much of this kind of pano work until I saw James' photographs. (of course in a slightly different sense, Sudek was also a master of this)
    You'd be amazed how small the demand is for pictures of trees... - Fred Astaire to Audrey Hepburn

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  4. #4

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    Rotating lens panoramics and field curvature

    Robert.
    To the best of my knowledge your analysis of both kinds of "panoramic" cameras is perfect.
    The rotating drum system transforms long straight lines into curves. Vertical shots with this kind of camera have a weird look except if you curve the final print for display ! This was demonstrated to me by a friend who owns a Noblex 150/120 rollfilm. the test image shown some stairs in an old house ; in order to restore the stairs in a realistic shape the final print had to be curved and the eye placed in the right position.
    The Noblex has an excellent tessar-type lens and image sharpness is not questionable. The other camera of this kind I have seen in action is the Alpa Rotocamera ; actually the camera was not manufactured by Pignons SA but by Seitz AG who continues to manufacture panoramic cameras under the brand : roundshot. The Alpa Rotocamera is fitted with a 6.8/75 mm grandagon-N and features a vertical shift adjustment plus a small reflex viewer !! Sharpness issues in this rare camera are never due to the optics but sometimes due to imperfections in mechanical synchronism between film advance (friction problems for un-perforated 120/220 rollfilm) and camera rotation.

    From a personal point if view I second you in the fact that I prefer orthoscopic views where straight lines remain straight.

    But as of 2005 in the digital era you may do some digital post-processing by stitching together several shots taken with a non-panoramic camera. Some specialised software allow you to choose either the cylindrical projection or the orthoscopic projection. Images are distorted according to the kind of projection you are using so you are no longer restricted to a single specialised camera, you can generate any kind of perspective as you wish Of course I assume here that the final image is a digital file for digital printing.



    Going slightly off-topic, a trick mentioned by a French photographer who uses digital stitching with a 24 m tilt+shift lens for a 35m camera is that before stitching images where a vertical shift has been mechanically applied, it is better to add a blank rectangle to the top or bottom of the image in order that the true optical axis is actually at the centre of the digital image file. Same would apply if you digitise a series of medium- or large-format film-images taken with shifted standards on your view camera. If you do not add the additional dummy image band, the stitching program may be confused and might fail to stitch properly.

  5. #5
    Mark Sawyer's Avatar
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    Rotating lens panoramics and field curvature

    Much of the "banana" curvature comes from having the horizon (or whatever straight horizontal line) high or low in the photo; this happens most obviously with ultrawide lenses. Run the horizon through the middle and it won't be so ovious.Swing-lens panoramic cameras often have a narrow vertical slit behind the lens that swings with it during the exposure to get rid of barrel distortion, which would really fuzz out the image since the distortion changes as the lens moves.
    "I love my Verito lens, but I always have to sharpen everything in Photoshop..."

  6. #6

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    Rotating lens panoramics and field curvature

    www.metiviergallery.com/artists/james/james.html
    check these out. as Tim said, not much in the way of curves.

  7. #7

    Rotating lens panoramics and field curvature

    Robert: here is a digital pan from 3 transparencies. 3 overlapping exposures and the left and right ones were done at 45 degrees from the center exposure.

    <html>

    a pittsburgh panorama

    <html>

  8. #8
    Ted Harris's Avatar
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    Rotating lens panoramics and field curvature

    I use a Noblex 150F frequently, it is often an 'assignment saver' for me. I also do a lot of landscape work with it. I have also use a Seitz Roundshot and a Fuji G617. For both technical details and an explanation of the differences between 'wide format' photography (e.g. the G617 or stitched images) and true panoramas (e.g. any of the swing lens or swing body cameras).

    You can eliminate most or all of the banana curvature by careful placement of the camera. The Noblex has two built in levels and as longas you are rigerous about leveling both horizontally and vertically and do not have straight lines at an angle int he picture you will get rid of most all of the curvature. The appealof the Noblex 6x12 format is that the field of view is ~146 degrees which approximates the field of view of the human eye. I cannot think of any landscapes I have done in the past several years where there has been any noticable curvature. Where I am working in very close for commerical work it happens once in a while. Go to http://www.meetinghouseinn.com/ and look at the image across the top of the page. That was done with the Noblex and could not have been captured any other way. Note that there is a bit of curvature (I was less than 3 feet away from the nearest point in the scene) but not objectionable.

  9. #9

    Rotating lens panoramics and field curvature

    If you really want to have fun, photograph a curved wall, like a church's nave with a Noblex.

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