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Thread: Alignment workflow (architechture)

  1. #11

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    Re: Alignment workflow (architechture)

    Quote Originally Posted by ibabcock View Post
    ... Doremus - I see your note about not using pan for leveling horizontals, but the whole premise is that I am not square face-to-face with the building, and so I want the lens and the film back together as a unit both to be square so shouldn't I use pan to level horizontals before resorting to rear swing? Fix verticals first, then horizontals, then fine tune composition with front movements only.
    Set up your camera as close to final position as possible. Then, use the pan and tilt to get the verticals correct. It doesn't matter if your tripod is level as long as you don't change anything after locking down the tripod head once you have the verticals correct. Then use rear swing to fine-tune the horizontals.

    The problem with using pan to get the horizontals correct is that if the tripod is just a tiny bit out of level, panning will skew the verticals that you just worked so carefully on, so you have to go back and re-do them, then you have to check the horizontals again... Using swing at this stage is faster by far. It should be a real time saver with a ball head too. Yes, if you swing the back, you'll have to swing the lens stage too to get focus, but you should be checking that anyway.

    Just ask a cinematographer how carefully they have to level their tripods and heads in order to do a decent pan shot. Tripods for still photography are not nearly as sophisticated as good cine tripods/heads either.

    With my method, you don't even have to worry about setting the tripod up level (another time saver and a blessing on uneven terrain). Eyeballing is just fine.

    Best,

    Doremus

  2. #12

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    Re: Alignment workflow (architechture)

    The roof will not be horizontal unless the camera is perpendicular to the wall of the building . I have had this issue for years. Also as mentioned above buildings are not actually built perfectly - things are often out of true.

  3. #13

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    Re: Alignment workflow (architechture)

    Quote Originally Posted by Robert Opheim View Post
    The roof will not be horizontal unless the camera is perpendicular to the wall of the building . I have had this issue for years. Also as mentioned above buildings are not actually built perfectly - things are often out of true.

    Maybe you meant parallel? Perpendicular means "at an angle of 90° to a given line, plane, or surface."

    Two horizontal (parallel) lines in the scene will only be rendered parallel on the film if the camera back (i.e., film) is oriented so that an imaginary horizontal line in it is parallel to both those lines (e.g., the façade of a building).

    Note that we can have converging verticals and nice parallel horizontal lines, so the film only needs to be "parallel" in one axis to get the horizontals right. Same for the verticals; we can have nice parallel verticals and converging horizontals (think an oblique view of a building façade).

    Note also that an axis line on the film has to be parallel to two parallel lines in the scene. It's real easy to get one line nice and horizontal, but have all the others converging... In fact, any scene with converging verticals or horizontals has one line it it (imaginary or not) that is parallel to the axis of the film.

    Getting both horizontals and verticals parallel requires the film plane to be parallel to the façade (assuming the façade is true...). Or, put another way, it requires that we have imaginary horizontal and vertical lines on our film plane that are parallel to two parallel lines horizontally and two parallel lines vertically, respectively, in the scene. It's a two-part procedure: get the verticals right, then get the horizontals right.


    Your camera back can be perpendicular to ground while doing this...

    Best,

    Doremus

  4. #14
    C. D. Keth's Avatar
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    Alignment workflow (architechture)

    He said it right. A horizontal roofline will only look perfectly horizontal when the lens axis is on a plane perpendicular to it. That satisfies the same conditions as your method of explaining the same thing.


    The verticals will only be parallel when the film plane is also vertical.


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    Last edited by C. D. Keth; 16-Feb-2020 at 21:01.
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  5. #15
    Unwitting Thread Killer Ari's Avatar
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    Re: Alignment workflow (architechture)

    I often work in carpentry so levels are plentiful in my house, but the top-shelf ones are quite expensive, not to mention unwieldy and not practical for photo use.
    I've found that Ebisu card levels give a good combination of accuracy and portability.
    Digital inclinometers are hit-and-miss for accuracy, even the more expensive ones are a bit of a gamble.
    Camera/tripod/ball head levels are ok to get you in the ballpark, but not very useful beyond that.

    Click image for larger version. 

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  6. #16

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    Re: Alignment workflow (architechture)

    Quote Originally Posted by C. D. Keth View Post
    He said it right. A horizontal roof line will only look perfectly horizontal when the lens axis is on a plane perpendicular to it. That satisfies the same conditions as your method of explaining the same thing.

    The verticals will only be parallel when the film plane is also vertical.
    Of course! The camera axis (really, a perpendicular line from the film plane) does need to be perpendicular to parallel lines in the scene in order for them to be rendered parallel on the film. I think so regularly in terms of film plane and "lens plane" (a là Scheimpflug, i.e. a plane perpendicular to the lens axis running through the optical center of the lens) that when someone says "the camera has to be perpendicular" I immediately think of the plane, not the axis. My mistake for misunderstanding and apologies to Robert!

    For getting parallels right, imagining the film plane, or the axis lines on the film plane, is easiest for me. It is really the horizontal and vertical axes of the film plane that have to be parallel to horizontal and vertical parallel lines in the scene, respectively, in order for them to be rendered parallel on the film. When both axes are parallel to the vertical and horizontal lines in the scene, the film plane is parallel to the plane in the scene. (Thanks Euclid...). Adding the extra perpendicular lines to the mix just makes it more complicated for me.

    The lens axis, on the other hand, can be tilted or swung away from perpendicular to the scene for whatever reason without affecting the parallel rendering on the film. The lens position determines the focus plane only; the film plane position relative to the scene determines the perspective and whether or not parallel lines in the scene are rendered parallel on the film. I use front tilt when photographing architecture often and the parallels are just fine

    Note further that you can get a roof line exactly horizontal even if the horizontal axis on the film plane is not parallel to the horizontal lines in the scene. Even with convergence, one line in the scene will always be parallel to the horizontal axis of the film plane. If we use the side-to-side tilt function of the tripod head to align a roof line with a horizontal grid line on the ground glass, but the film plane is not parallel horizontally to the scene, all the other horizontal lines in the scene will converge. This is a problem for beginners, who many times just align one line in the scene. The result is often that all the other horizontal lines in the scene converge slightly, which can be disconcerting (this applies equally for verticals, just rotated 90°).

    By making sure two parallel lines in the scene are correctly aligned with the grid on the ground glass, either vertically or horizontally or both, we automatically get the film axes in the right position. When we align both vertical and horizontal parallels this way, the film plane is then parallel to the plane in the scene.

    It sure is a lot harder to describe all this precisely that to do it!

    @Ari: I have levels on all my cameras and use them when setting up. However, I've found that no matter how good the levels are, orienting the scene to the grid on the ground glass is almost always needed. Sometimes it's just a little tweak, sometimes more. Plus, as mentioned above, buildings are not always plumb or level. Visually compromising the elements (lines) in the scene is often needed and using the ground glass helps get things as pleasing as possible.

    Best,

    Doremus

  7. #17

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    Re: Alignment workflow (architechture)

    The Ebisu Card Levels are quite good.
    Th carpentry levels I have (not cheap ones, not super expensive) have not been as reliable; I only trust one of them at this point; the rest are for making straight lines.

    Quote Originally Posted by Ari View Post
    I often work in carpentry so levels are plentiful in my house, but the top-shelf ones are quite expensive, not to mention unwieldy and not practical for photo use.
    I've found that Ebisu card levels give a good combination of accuracy and portability.
    Digital inclinometers are hit-and-miss for accuracy, even the more expensive ones are a bit of a gamble.
    Camera/tripod/ball head levels are ok to get you in the ballpark, but not very useful beyond that.

    Click image for larger version. 

Name:	card level.jpg 
Views:	15 
Size:	32.3 KB 
ID:	200781

  8. #18

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    Re: Alignment workflow (architechture)

    Top digital level (no brand name) stay away from. Bottom pocket level... went to the hardware store many years ago and they had a bunch FS. Most were faulty. Bought 2 good ones. Brand is Stevens. One resides in a stream under a bridge in Granville, Ma. If you come across any FS, test them and if they are accurate definitely buy them. Mine normally has a piece of fluorescent webbing tied to its pocket clip, so I hopefully won't accidentally leave it in the field. Much prefer it to camera levels. FYI, when I bought my Sinar X, two of its levels were off "out of the box".
    Attached Thumbnails Attached Thumbnails levels.jpg  

  9. #19
    Unwitting Thread Killer Ari's Avatar
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    Re: Alignment workflow (architechture)

    Quote Originally Posted by Doremus Scudder View Post
    @Ari: I have levels on all my cameras and use them when setting up. However, I've found that no matter how good the levels are, orienting the scene to the grid on the ground glass is almost always needed. Sometimes it's just a little tweak, sometimes more. Plus, as mentioned above, buildings are not always plumb or level. Visually compromising the elements (lines) in the scene is often needed and using the ground glass helps get things as pleasing as possible.

    Best,

    Doremus
    Hey Doremus,
    I remember a post of yours (in reply to my questions) from a long time ago where you said exactly the same thing, and I've remembered it ever since.
    That is, use the levels to get you in range, but in the end always trust what you see in your viewfinder/GG to determine correct leveling.
    Great advice that I tell everyone to this day.

  10. #20
    C. D. Keth's Avatar
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    Re: Alignment workflow (architechture)

    Quote Originally Posted by Doremus Scudder View Post
    It sure is a lot harder to describe all this precisely that to do it!
    Isn’t that the truth? These are things that so many of us just know but are surprisingly hard to define and explain. I TA’d an introductory cinematography class in college and almost everything was like that. I had to help define things that are more often just felt and known. It was often a surprisingly difficult task.


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