Leveling a field camera

Discussion in 'Large Format Cameras and Accessories' started by Kevin Kehler, Aug 27, 2012.

  1. Kevin Kehler

    Kevin Kehler Member

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    So I set up the tripod and 3-way tripod head, both of which are rated more than enough to hold the camera. I leveled the tripod and head using my trusty spirit level I keep in the camera bag. I then attached the camera to the tripod head and and re-leveled the tripod, placing the spirit level on the block under the bellows. I put the ground glass on and ensured all adjustments are neutral (no tilts, swings or shifts). However, the building directly in front of me does not line up with the etchings on the ground glass: one of the walls starts 1-2mm on the left of one line and ends up 1mm to the right of the line but if I adjust the tripod, I can straighten it all out where the wall runs parallel to the line (I think I can assume the etched lines are straight as it is a professionally made ground glass). However, the spirit level under the block now reads a non-level with a tilt to one side.

    Which reading do I take as accurate? My initial reaction was if the camera is leveled properly, then use that. However, I also considered that what-you-see-is-what-you-get and if the building is not straight on the ground glass, why would it be straight on the film? Is it possible my adjustments were not truly neutral which caused the problem?

    Thanks in advance.
     
  2. TimFox

    TimFox Member

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    I have found it necessary to put a level directly on the ground glass, or on the ground-glass frame nearby, to ensure that the film plane is vertical.
    This is what governs the convergence you see.
    However, I have sometimes pulled my head out from the dark cloth and found that the building was tilting in reality.
     
  3. degruyl

    degruyl Member

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    If you want the building to be straight in the photograph, it has to appear straight on the ground glass. This is why lenses with movements are called perspective correction lenses in the small format world.

    If you want the camera to be level, it has to be level (actually, the film plane and lens have to be plumb). Those two things are separate.

    Maybe I'm missing something, but the base plate of a field camera has very little (none) impact on the image, so leveling that is only in aid of squaring off the front and rear standards.
     
  4. Leigh B

    Leigh B Member

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    Did you level the damera side-to-side?
    One of the levers on your tripod head should allow movement on this axis.

    Bubble levels come in all different accuracies and resolutions. It's possible yours is not well-suited to the task.

    BTW, levels are self-calibrating.
    Find a flat surface like a counter top (need not be perfectly level), and tape a shoebox onto it.
    Put your level in one corner of the shoebox, up against the side, and note the reading.
    Turn the level around 180° and repeat. Compare the two readings.
    They should be identical. If they're not, the level is inaccurate.

    The previous comments about the ground glass are important.
    The GG is the final arbiter of what will be on the film, regardless of what your levels say.
    Use a level that measures on two planes, and put the vertical one against the GG. Adjust the back so the GG is vertical.

    That still does not evaluate camera tilt side-to-side, as discussed above. Adjust the camera as needed.
    If necessary, adjust the camera tilt so the building vertical lines up with grid on the GG.

    - Leigh
     
    Last edited by a moderator: Aug 27, 2012
  5. David A. Goldfarb

    David A. Goldfarb Moderator Staff Member

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    I've had a level on the tripod legs, another on the platform of the tripod head, and another on the camera, that don't agree. I trust the one on the camera usually most of all, but you still have to confirm on the groundglass, presuming that the groundglass is installed straight in the back and the back is straight on the camera, which may not be the case. Then buildings sometimes lean...
     
  6. Leigh B

    Leigh B Member

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    Measurements on the camera itself are the only ones that actually matter.

    Having the platform/head level may be desirable if you want to change axial position front/back or side-to-side.

    Setting the GG and the lensboard parallel (vertically) can rely on readings from the same level, even if the level
    itself is inaccurate, as long as the same end is up for both measurements.

    - Leigh
     
  7. David A. Goldfarb

    David A. Goldfarb Moderator Staff Member

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    It's relatively unusual not to have to pan the camera a bit, so I like having a level platform to pan from, although one can always make a final adjustment after panning.
     
  8. Leigh B

    Leigh B Member

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    I agree. I do the same thing, for the same reason.

    My comment was addressing the question of disagreement among level readings at different points in the system.

    - Leigh
     
  9. ic-racer

    ic-racer Member

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    To get vertical lines of the building straight you have to have the back perfectly plumb. In fact it only needs to be leveled by eyeball approximation because you can correct for not being level when printing by rotating the easel one way or the other.
     
  10. cliveh

    cliveh Subscriber

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    Levelling a field camera - I don’t understand this concept, as surely image making is not about levelling. The photographer decides on the composition, which may mean putting the horizon or whatever, horizontal, or at an angle. The eye determines this, not a spirit level. How can you let science dictate the aesthetic?
     
  11. Leigh B

    Leigh B Member

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    It's pretty simple actually.

    You adjust the camera supports so that the support platform is level, then adjust the
    ground glass and the lensboard so they're both vertical.

    Those adjustments are important in some types of photography, not in others.

    If you need it, do it. If not, ignore it.

    If you don't understand the concept, you need to study basic photography.

    - Leigh
     
  12. Dan Fromm

    Dan Fromm Member

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    Agree fully. That's why I have a Manfroto 138 leveler between tripod and head. If I make it level, there's no need to adjust after panning.
     
  13. markbarendt

    markbarendt Subscriber

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    The film is the thing that matters the most.

    So if the back standard (the film) is level right to left and "flat" in relation to the face of the building, in the sense that if you walked up to the building you could paste the film to the face of the building without changing its orientation; then the verticals and horizontals should look exactly vertical and horizontal right to left. Lines leading away from the camera into the distance will still converge.

    This happens regardless of how the front standard (the lens) or the base of the camera are oriented, just the orientation of the film to the subject.

    Front shift, rise, and fall change what the film sees. Rise for example is used to make the camera see up and is very normal for shooting tall buildings from street level, a cliche example is a church steeple. Fall is regularly used for portraits, it allows the back/film/ground glass to be head high, level, and square but with the lens lower the framing can be from toes to hair with little wasted film. Shift works the same just sideways.

    Front tilt and swing manipulates the "plane of sharp focus". For the face of a building you simply square up like was described above for the back, that church steeple or a standing portrait can then easily be focused to be sharp top to bottom without stopping down to f/64. If the subject is a ridge that crosses your composition at a diagonal you can swing the plane of sharp focus to match, schliemflug works in both horizontal and vertical.

    Generally the biggest limit to these movements is the image circle the lens projects.
     
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  15. Kevin Kehler

    Kevin Kehler Member

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    I am using a Manfrotto 3-way head so it is very easy to adjust and generally speaking, while the bubble levels in the head are fairly accurate, I don't rely on them. I was more uncertain if I should trust a spirit level resting on the camera or image projected on the ground glass.

    David, I also never considered whether the ground glass is straight when it was installed - something for me to check tonight.

    Clive, I agree the aesthetic is more important than the technical but flaws in technique detract from the aesthetic. I know when I have a good image, I want to make sure I am capturing the image as I see it so I don't have more work than necessary in the darkroom.

    Really enjoying this discussion. Thanks all!
     
  16. markbarendt

    markbarendt Subscriber

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    Glad I could help.
     
  17. TimFox

    TimFox Member

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    Convergence

    When photographing a conventional building, with vertical parallel lines, it is a convention of Western art (see Caneletto for superb paintings that show this) that the vertical lines not converge. This is why one makes the film plane/ground glass vertical/plumb. What is most annoying is a slight convergence, which looks careless. Strong convergence can be used to exaggerate height, e.g., shooting a tall building wall lying on the ground, for effect. Convergence of horizontal lines indicates perspective (strong or weak).
     
  18. Kevin Kehler

    Kevin Kehler Member

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    Now that I am at home, playing with the back and the ground glass, there is about 1-2mm of play on both horizontal and vertical positions. So, when the back is put on the camera, the ground glass moves which could account for my difference. However, I will need to try it out before I can "close the file".

    Mark, you need to copyright your response, it is one of the better explanations of camera movements I have read. I haven't adequately learned camera movements yet, partially due to not using the camera enough but also because I am not really sure what I am doing.

    Another quick question, my camera has rear swing but not front swing. If I wanted to shift a diagonal plane-of-focus from far away left to close to the camera right, I would swing the rear standard right-closer-to-lens-board and left-farther-from-lens-board to use schliemflug to create my plane of focus. However, haven't I now altered the shape of the image and would perhaps be better off stopping down? I realize aesthetic considerations triumph and it wouldn't matter much in an irregular shape (like tree roots) but thought I would ask. What I really need to do is shoot paper negatives, so I can practice and not feel bad about wasting film.
     
  19. markbarendt

    markbarendt Subscriber

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    Thanks again Andreas.

    Ok on to your question.

    Yes you can swing the plane of focus with the rear standard, yes you alter the shape and geometric relationships in the composition, and yes for many subjects it doesn't matter.

    Personally I try to think of scheimflug as a tool to control what's in focus, not necessarily a tool to get everything into focus.

    Shifting requires that lens and film remain parallel, if your camera can do rise and fall, you could turn those movements into shift by tilting the camera 90 degrees. The lens and film don't care but that may not be practical.

    By all means get out and practice.
     
  20. Leigh B

    Leigh B Member

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    Absolutely. Experience is the best teacher.

    View camera movements are a rather unique subject. Even basic movements require insight and understanding.

    Complex and combined movements can be very involved, and can achieve some wonderful effects.

    Do it and learn. Take one movement at a time; learn it and understand it, then move on to the next.

    - Leigh
     
  21. Diapositivo

    Diapositivo Member

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    In my experience, using small format, levelling the camera with bubble levels of the kind which are commonly used in photography, i.e. with a small base, there easily is a mistake up to 0.2° or 0.3°. That might not be noticeable with most subjects, but it is with certain architectural subjects and, in general, it is if you draw rulers on the image.

    I think one should first level the camera (or both the tripod and the camera if more than one picture is to be taken with a different angle) and after that, if the subject has a certainly vertical line which can be used as a reference against a ruler, fine-tune the levelling.

    Finding a suitable vertical line in the frame is not so easy though. Lamp posts are very unreliable, just like any pole in general. Outer edges of old buildings are also unreliable as they might have some scarp, albeit small. In Paris I saw innumerable XVIII century buildings with a very pronounced scarp and windows following it, so that basically there is no element on the façade to be relied upon. Water drains are also not necessarily very vertical.

    Fabrizio

    PS It goes without saying that while using small format the vertical line to be taken as measure is to be on the exact centre of the frame.
     
  22. cliveh

    cliveh Subscriber

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    Why?
     
  23. Diapositivo

    Diapositivo Member

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    Because unless you are taking a picture of a subject which has a face exactly parallel to the focal plane there are going to be converging lines everywhere and those converging line are not good for camera orientation.

    Let's make a very obvious example.

    You are in front of a relatively tall building. You have a small format camera. Let's make it short and decide that you are going to point the camera up in order to have the building enter the frame.

    As is universal experience, all the lines which in the buildings are parallel in your frame will be converging. The lines which start from the same plane (such as those formed by the windows of the façade) will converge to a vanishing point.

    Now imagine your camera is not perfectly horizontal, and imagine the focal plane is exactly parallel to the plane of the façade.

    If the camera is bent "to the right", the vanishing point will fall on the left part of the frame.
    If the camera is bent "to the left", the vanishing point will fall on the right part of the frame.
    When the camera is exactly horizontal, the vanishing point will fall exactly on the middle of the frame, i.e. when the vanishing point falls along a line in the middle of the frame, the camera is exactly horizontal.

    Now visualise this steel and glass building with plenty of vertical lines. When the central line (central in your frame, it doesn't matter if it is in the middle of the building façade) is vertical, your camera will be levelled.

    First case, camera parallel to façade:
    https://www.imagebroker.net/thumbnails/16/26/1626984.jpg

    The subject will "level your camera" as the vertical line which is in the centre of the frame will be the line which, if vertical, will make the frame exactly horizontal. But in this case, in fact, all lines could be used as a valid gauge. The real interest arises when the façade is NOT parallel to the focal plane.
    In this case, your camera is levelled when, and only when, a line which is vertical in reality is also vertical in the CENTRE of your viewfinder.

    Examples of camera not parallel to façade:

    https://www.imagebroker.net/thumbnails/16/26/1626996.jpg

    https://www.imagebroker.net/thumbnails/16/27/1627000.jpg

    The same rule applies. If the imaginary (or real) line in the centre of your frame, which is "vertical" in your frame, corresponds to a line of the façade (which is vertical in reality, that is) the camera MUST be exactly horizontal.

    Fabrizio

    PS The building is the ENI building in the EUR district of Rome.
     
    Last edited by a moderator: Aug 28, 2012
  24. cliveh

    cliveh Subscriber

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    So if I follow this advice, I will get verticals and horizontals parallel to my frame edges. Is that correct?
     
  25. Diapositivo

    Diapositivo Member

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    I don't understand the question.

    The rule is: your camera is horizontal if an existing line which is vertical in nature coincides with a vertical line in the centre of your viewfinder. Edges must be disregarded completely. Trying to align anything with the edges of the viewfinder is a sure way to have a tilted horizon.

    Aligning lines to the frame edge is the typical mistake people make as it is in many introductory books to photography. That doesn't work. In the first ENI building example in my previous post it would work, but in the second and third example it would not. The centre line always works.
     
  26. cliveh

    cliveh Subscriber

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    Thank you, I think I now understand.