View camera alignment for "full frontal architecture"

Hi folks,

I am having trouble aligning my camera for a special series I am working on for some time. I try to explain:

I want to do "full frontal" photographs of building fronts, so that the optical axis (assuming all movements are zeroed) is exactly orthogonal to the wall of the building (in other words, the camera front and back is exactly parallel to the building). Furthermore, it needs to be "centered", so let´s say the horizontal middle of the building is exactly in the middle of the GG without any perspective distorsion. I will then later use rise/fall vor framing only. An example is the following image (courtesy of Barbara Wolff):

Attachment 111111

My camera (Technikardan) allows full front and back movements. But I am havign serious problems to achieve orhtogonal alignment of the optical axis.
I currently do it as follows:

0. Set up tripod, level the camera with spirit levels (I checked the accuracy, they are OK). I use a standard 3-way pan/tilt head. The pan is below both tilts.
1. Zero all movements.
2. Align the camera by panning, so that all horizontal lines are parallel to the GG lines. Vertical lines are parallel already because of the spirit level alignment.
Now the first problem occurs: Strangely, once it looked to me that the lines in the upper part of the building were parallel to the GG lines when the ones in the lower part are not and vice versa (depending on the amount of pan used). It was difficult to tell, since I am not sure if all lines on the building were acutally level with high precision. Anyway, when I had some of these lines parallel, it was clearly visible that the pan was too extreme and the back was not parallel to the building front. So I had a look at my spirit level for left/right levelling of the back, but it looked ok. Was it lens distortion? I use a 5,6/150mm APO-Symmar, which is screwed to the lensboard correctly (the threads do join well). I have to say that I did not check if the spirit level changes with panning...just thought about that now.

3. After maybe 20-30 minutes of fiddling with the pan setting, I finally got all lines parallel (more or less)

4. So, I tried to "center" the camera horizontally by shifting both standards in the same direction (so there is no left/right perspective added). Basically, the same as if you would move the tripod left/right parallel to the building (which is not possible precisely). This was again 20-30 minutes of trial and error, really annoying, touching the pan again, starting from step 1 again and so on. Finally by chance, I obtained an acceptable composition/alignment.

As you might see, this took almost one hour and I got really upset. I feel that there must be a better, faster and more reliable way to obtain an acceptable result. Maybe I should change the order of movements?
Any advise would be highly welcome!

Best regards,
Jan

Update: I just found the idea to use a small mirror, which could be attached to the building´s front. When you can sse your lens in the center of the mirror on the GG, it should be aligned perfectly perpendicular to the mirror. However, this does not solve the problem that the mirror needs to be exactly parallel to the building, and that it has to be attached to the building.

Any other ideas?

Quote:

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Originally Posted by Rollinhofuji

Any other ideas?

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For a building like in the picture, I'd center myself using a tape measure. Have an assistant hold the tape (or string) against the right edge of the building and use chalk to mark an ark near where you estimate the ideal tripod position to be. Do the same (without changing the length of the tape measure or sting) from the left edge of the building. Again make an ark with chalk. The intersection of the two arks should be a point perpendicular to the center of the building. If the building does not have doors in the exact center, again use the tape measure to find the exact center of the building. So you would put the tripod at the intersecting chalk marks and aim at the middle of the building. If you camera's movements are indeed parallel (you have had them checked with a laser?) then you should only need to adjust rise to get your framing.

Hey ic-racer, thanks!
Plain old geometry - this seems to be practicable, easy and should definitely be very accurate. I am embarrassed, since I studied physics and have failed to find such a great solution on my own...
Regarding the parallelity of movements I did not check it yet, but will do that (or let Linhof do it, sicne the camera needs some service anyway).

Thanks again!

Since you are panning so much to set up your camera, I'd also suggest levelling your tripod, as you hinted at in the original post.

With a mirror you would need to be a couple feet away in order to see the camera's reflection.

What about a laser rangefinder?

Been shooting architecture professionally since 1978. Few things in the architectural world line up perfectly believe it or not. If you get the building lined up the line in the concrete may very likely be off then the building will look off. Its more about if the building "feels correct" as nothing is ever perfect. If you are scanning your film I would do the best in camera aligning the standards etc. without being obsessive about it and then do some of the final alignment in PS so that it looks centered.

The image doesn't have to be perfect to feel like its "full frontal" and in many cases a perfect full frontal may not even be possible.

Quote:

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Originally Posted by Kirk Gittings

The image doesn't have to be perfect to feel like its "full frontal" and in many cases a perfect full frontal may not even be possible.

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+1 from another architectural photographer.........L

Quote:

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Originally Posted by Ari

Since you are panning so much to set up your camera, I'd also suggest levelling your tripod, as you hinted at in the original post.

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I'll confirm what Ari writes. Levelling the top plate of the tripod is critically important. If there is the slightest tilt in the tripod top plate a camera perfectly orthogonal at one pan setting will be "off" if turned a little bit. My tripod (Manfrotto 028B) features a sensitive bulls-eye bubble level but even it's not accurate enough to guarantee "no tilt" at any pan setting.

Quote:

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Originally Posted by Rollinhofuji

Hi folks, I am having trouble aligning my camera for a special series I am working on for some time. I try to explain:

I want to do "full frontal" photographs of building fronts, so that the optical axis (assuming all movements are zeroed) is exactly orthogonal to the wall of the building (in other words, the camera front and back is exactly parallel to the building). Furthermore, it needs to be "centered", so let´s say the horizontal middle of the building is exactly in the middle of the GG without any perspective distortion....

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Step 1: your tripod position needs to be on a line centered and at right angles to the face of the building. If you use shift to center the image, the optical center will not be in the middle of the frame. (This is a great tool, BTW, but not what you want, obviously). Usually eyeballing where the center is is good enough, but if not, get a rangefinder or long tape measure and measure to the edges of the building. Alternately, you can use the camera itself: point the camera at the center of the building (after leveling, of course, see below). If the horizontals don't line up, you are in the wrong place. Move your tripod and try again (this can be rather fast once you get the knack).

Quote:

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Originally Posted by Rollinhofuji

My camera (Technikardan) allows full front and back movements. But I am having serious problems achieving orhtogonal alignment of the optical axis.

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You don't want to use any camera movements except rise to get what you want.

Try this. Set up and level your tripod (not really necessary, but it helps save time). Mount the camera (making sure it is in "zero" position first) and use the bubble levels to level it roughly (note: bubble levels are only for rough leveling; use the grid on your ground glass for the fine work).

Now observing the image on the ground glass, use the side-to-side tilt on the tripod head to get a vertical line in the very center of the ground glass perfectly aligned.

Once you have that, use front-to-back tilt on the tripod head to align verticals at the edge of the frame. Once your verticals are all aligned on the grid, you can be assured that your camera back is parallel vertically.

Now, with the camera pointed at the very center of the building (I assume you have set up so that this was the case to begin with, but just to be sure...) check the horizontals. If they are off, you are in the wrong place! Yes, you could pan and then use shift to center the image, but then the middle of the building will not be the optical center of the photograph. If you have set up carefully, the horizontals should be fine; if not, move the appropriate direction (you can tell from which way you have to pan to get the horizontals correct. If you have to pan right, move the camera left, and vice-versa).

Use front rise to get the top of the building where you want it.

Double check the horizontals and verticals, then shoot.

I'll point out some of your mistakes below:

Quote:

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Originally Posted by Rollinhofuji

I currently do it as follows:

0. Set up tripod, level the camera with spirit levels (I checked the accuracy, they are OK). I use a standard 3-way pan/tilt head. The pan is below both tilts.
1. Zero all movements.
2. Align the camera by panning, so that all horizontal lines are parallel to the GG lines. Vertical lines are parallel already because of the spirit level alignment.

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You don't want to align horizontals this way if you want the optical center to be the center of the building. You need to position the camera correctly and then simply point it at the center of the building. If the position is correct, the horizontals will be correct. See above.

Quote:

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Originally Posted by Rollinhofuji

Now the first problem occurs: Strangely, once it looked to me that the lines in the upper part of the building were parallel to the GG lines when the ones in the lower part are not and vice-versa (depending on the amount of pan used). It was difficult to tell, since I am not sure if all lines on the building were actually level with high precision. Anyway, when I had some of these lines parallel, it was clearly visible that the pan was too extreme and the back was not parallel to the building front. So I had a look at my spirit level for left/right levelling of the back, but it looked ok. Was it lens distortion? I use a 5,6/150mm APO-Symmar, which is screwed to the lensboard correctly (the threads do join well). I have to say that I did not check if the spirit level changes with panning...just thought about that now.

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If horizontal lines at the top of the frame are parallel to the grid on the ground glass, but the ones on the bottom are not (or vice-versa) then your camera is not level vertically. You should do that step first, for the center and then the edges, using tripod head movements as described above. If the verticals are correct and you still have this problem, then is is the building that is likely not perfectly square (settling happens!). Then you'll have to compromise visually on what is most pleasing.

Quote:

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Originally Posted by Rollinhofuji

...
4. So, I tried to "center" the camera horizontally by shifting both standards in the same direction (so there is no left/right perspective added). Basically, the same as if you would move the tripod left/right parallel to the building (which is not possible precisely). This was again 20-30 minutes of trial and error, really annoying, touching the pan again, starting from step 1 again and so on. Finally by chance, I obtained an acceptable composition/alignment.

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Shifting both standards is the same as moving the tripod a small amount, and a good tool for very fine adjustment. Get as close to center with your tripod placement and you can use this trick to good advantage.

Again, don't pan to adjust horizontals. Point the camera at the center of the building and check the horizontals. If they are not right (after verticals have been aligned, of course) then your camera position is wrong. Move the tripod and set everything up again if needed.

FWIW, as hard as I try, I sometimes have to fine tune my perspective control in the darkroom. Don't be afraid to do this either (or do it digitally if you use a hybrid work-flow).

Best,

Doremus