Page 1 of 2 12 LastLast
Results 1 to 10 of 17

Thread: Front tilt?

  1. #1

    Join Date
    Nov 2008
    Location
    Toronto
    Posts
    384

    Front tilt?

    This is a shot I took last year (the first, and so far only, time I've shot LF... until my new gear arrives). I noticed in the scans that the top of the building in the corners was a little soft. Could this have been fixed with a little front tilt? Or would that have introduced problems elsewhere?


  2. #2

    Join Date
    Sep 2009
    Location
    Athens, Greece
    Posts
    182

    Re: Front tilt?

    If you want everything sharp in this picture, tilts won't help. You basically have a deep box here, where we see all the sides (except for the top). Tilting/Scheimpflug basically helps when you can reduce the areas you want sharp to become something around a slice.

    You'd have to stop down the lens for this one. But given the scale I'd say it should be doable.

  3. #3
    Moderator
    Join Date
    Apr 2009
    Location
    Northern Virginia
    Posts
    4,491

    Re: Front tilt?

    Tilting the lens tilts the plane of sharp focus. So, the answer to your question depends on what you want to be in focus. If you left the lens board vertical and just used the rise to correct perspective, the focus plane should be vertical. Then, it would depend on what you focused on. If the buildings are in focus at the edges in the middle of the frame, and if you didn't use tilts, then the upper corners should be equally in focus.

    So I don't think that's your answer.

    I suspect that you found the edges of the coverage of the lens you used. Some lenses, particularly older designs, go a bit soft before they go dark. Some of the newer wide-angle designs try not to do that, but still do to some extent.

    Check to make sure you didn't use tilts accidentally. Are the lens and film planes square on your camera? Sometimes, a strong rise with a wide lens will twist the bellows such that it fights back and throws the camera out of square.

    Rick "who would not use tilts for an image like this" Denney

  4. #4

    Join Date
    Nov 2008
    Location
    Toronto
    Posts
    384

    Re: Front tilt?

    The lens plane and film plain were square (Sinar F1 with bag bellows), and only front rise was used. The lens was a 90mm Grandagon N, and I shot at f22.

  5. #5
    Moderator
    Join Date
    Apr 2009
    Location
    Northern Virginia
    Posts
    4,491

    Re: Front tilt?

    Quote Originally Posted by Sean Galbraith View Post
    The lens plane and film plain were square (Sinar F1 with bag bellows), and only front rise was used. The lens was a 90mm Grandagon N, and I shot at f22.
    What did you focus on?

    The out-of-focus areas that are still nominally within the depth of field might show a little curvature, depending on the situation.

    And, as the owner of a Sinar F with an F2 front standard, I can say with some certainty that it's eaiser to push the F1 front standard out of whack than it seems like it ought to be. But the bag bellows should have minimized that.

    At what magnification do you see the loss of sharpness?

    Rick "running out of ideas" Denney

  6. #6

    Join Date
    Nov 2008
    Location
    Toronto
    Posts
    384

    Re: Front tilt?

    I can see a change in focus in the scan above, even without magnification. I've also scanned it on an imacon and printed it at about 28x36, and it is noticeable. (the scan above is a reduced version of the imacon scan).

    I was focusing on the foreground rubble pile line.

  7. #7
    Don Nelson
    Join Date
    Jul 2008
    Location
    Portland, Oregon
    Posts
    275

    Re: Front tilt?

    First of all, either the building nearest you was tilted outwards (doubtful)
    or
    your rear standard wasn't exactly perpendicular to the ground (its an easy check -- take the picture and put it in powerpoint then draw a square...)....your back was tilted slightly forward from perpendicular.

    Since its a grandagon-n 90, the edges aren't soft (I have one) or you dropped it....
    So presuming the front standard is near vertical or even parallel to the rear standard
    and
    that your depth of focus was set looking at the ground (top of the groundglass) and infinity, then you'd need just a bit more depth of focus at for the upper corners of the building which are at the bottom of the groundglass.

    You wouldn't see this if you stopped down just a bit further. Or squared up the back to the ground(and verticals in the building)

    try it with powerpoint or some other drawing tool that provides boxes....even photoshop...you'll see the verical nearest to you isn't parallel to the sides of the image.

  8. #8

    Join Date
    Nov 2008
    Location
    Toronto
    Posts
    384

    Re: Front tilt?

    The lens was a rental, so I have no idea if anything happened to it previously. It at least looked in great shape. I'm going under the assumption this was entirely operator error. :-)

    Thanks for the advice! I'm looking forward to putting it into practice.

  9. #9
    ki6mf's Avatar
    Join Date
    Nov 2007
    Location
    Austin, TX
    Posts
    593

    Re: Front tilt?

    I agree with the advice here Tilt for DOF should be avoided with tall fore ground objects because the near focus is tilted and a tall object sticks up into the our of focus part of the shot. I have not had this problem with my Grandagon 90MM either. Could it be you were near the edge of the focus circle and with the aperture was getting some softness?
    Wally Brooks

    Everything is Analog!
    Any Fool Can Shoot Digital!
    Any Coward can shoot a zoom! Use primes and get closer.

  10. #10

    Join Date
    Nov 2008
    Location
    Toronto
    Posts
    384

    Re: Front tilt?

    It is entirely possible, though I have no idea if that is the case.

Similar Threads

  1. Meaning of yaw
    By Leonard Evens in forum Style & Technique
    Replies: 41
    Last Post: 10-Apr-2008, 09:52
  2. Can somone check a Korona front tilt mechanism?
    By ericantonio in forum Cameras & Camera Accessories
    Replies: 2
    Last Post: 24-Mar-2008, 20:14
  3. Question about front axis tilt on ebony 45s
    By Julian Boulter in forum Style & Technique
    Replies: 13
    Last Post: 13-Aug-2006, 10:03
  4. Optics Involved in Forward Tilt and Front Rise
    By Howard Slavitt in forum Style & Technique
    Replies: 11
    Last Post: 9-Aug-2006, 14:23
  5. front tilt and depth of field (WYSIWYG) ?
    By adrian tyler in forum Style & Technique
    Replies: 10
    Last Post: 29-May-2004, 19:22

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •