Align optical axes to rail axes

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Antal
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Align optical axes to rail axes

Post by Antal »

Hi,
If the optical axe is not perfectly parallel to the rail axe, the images in the stack will slightly shift.
Is there an easy way to align them?

ray_parkhurst
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Re: Align optical axes to rail axes

Post by ray_parkhurst »

Antal wrote:
Fri Oct 28, 2022 8:55 am
Hi,
If the optical axe is not perfectly parallel to the rail axe, the images in the stack will slightly shift.
Is there an easy way to align them?
Only way I know is brute force. Hopefully someone can recommend an elegant method as I'd love to hear something easy.

rjlittlefield
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Re: Align optical axes to rail axes

Post by rjlittlefield »

The simplest way I know to check alignment goes like this:
  • Mount an ordinary macro lens on the camera.
  • Place a subject where the lens can focus when the camera is at both ends of the rail.
  • Move the camera to one end of the rail, focus, and take a picture.
  • Move the camera to the other end of the rail, focus, and take a second picture.
  • If the axes are perfectly aligned, then the same point on the subject will appear in the center of both pictures.
  • If the center of frame moves, then some trial and error will converge pretty quickly to a good alignment.
  • The test will be most sensitive when the subject is as close as possible to the rail, and still able for the lens to focus.
If you have access to machine tools, then you can probably make a jig that will help you get the front of the lens perpendicular to the rail axis.

All that said, I don't think I've ever needed to go to such pains. Just lining up the rail and the camera+lens carefully "by eye" gets them close enough to avoid artifacts in the stacking.

--Rik

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