How can I align a camera so the lens points straight down at a subject?
Asked 6/24/2022
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I’m photographing small 3D model parts from directly above so the images can be used for accurate CAD tracing. To reduce perspective and parallax errors, I need the camera’s optical axis to be as close as possible to perfectly perpendicular to the floor or shooting surface.
I’ve tried using spirit levels on the lens and camera body, and also a plumb line, but those methods are awkward and not very precise. Is there a reliable way to ensure the lens is pointing absolutely vertically downward?
Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0
Photography Stack Exchange contributor
4y ago
2 Answers
12
A good way is to set a mirror flat on the floor, and check the reflection of the lens in the viewfinder. It should be exactly centered:
- This actually ensures that the lens axis is perpendicular to the plane of the shots, so it also works to shoot something vertical or at an angle (but you have to find some way/person to hold the mirror)
- The hardest part is finding a suitable mirror which is not encumbered by a frame that could add an angle. Edit: signal mirrors as found in survival kits could be good candidates, the hole in the center makes it easy to position them (or mark their position).
Originally by user75947. Source · Licensed CC BY-SA 4.0
user75947
4y ago
0
Generated from our catalog & community — verify before relying on it.
Yes. A simple, accurate method is to use a flat mirror on the shooting surface. Point the camera down at the mirror and adjust the camera until the reflection of the lens appears exactly centered in the viewfinder/live view. When that happens, the lens axis is perpendicular to the mirror plane, which is what you want.
Another good option is a clear alignment jig placed under the lens: for example, a short clear acrylic tube with marked rims, or a clear acrylic/glass block with two centered dots or crosshairs on opposite faces. When the camera is correctly aligned, the two marks/rings will appear concentric or superimposed.
These methods are generally more precise than checking the outside of the lens or camera body, because they reference the optical axis rather than the housing. They also work for any flat shooting plane, not just the floor.
For best results, also make sure the subject lies in a plane parallel to the sensor and keep the camera centered over the object.
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