Request for guidance on calibrating fixed-focus cameras in OpenPnP

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Rambo Jon

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Jul 27, 2025, 4:13:19 AM7/27/25
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Here's the revised English text, incorporating your requested changes:
"I am currently setting up a Pick and Place machine using OpenPnP with fixed-focus cameras. I am facing a challenge in calibrating the primary and secondary fiducials because I am unsure if the camera is capable of adjusting its focal length despite its fixed focus. I am stuck at these steps until I can get the necessary procedures.
Problem:
 * If both primary and secondary fiducials are set to the same Z level, will this affect the accuracy of the 3D calibration?
 * How can I compensate for the missing Z data in this case?
My questions to the community:
 * What is the optimal procedure for calibrating the secondary fiducials when using fixed-focus cameras?
Thank you for your time, and I look forward to your feedback.
Regards,
Rambo Jon"

vespaman

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Jul 27, 2025, 9:50:50 AM7/27/25
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Hi Rambo Jon,

Using fixed focus cameras are the normal way, so your setup is normal. You are not supposed to adjust focus to the primary/secondary, it should be the set and forget. 

As you are asking, I suspect you are experiencing problems in this stage of your setup. Can you give us some pictures on how the image looks like on primary resp secondary?
Issues that can cause trouble here includes lighting, the quality of the fiducials and general optics/distorsion.

 - Micael

tonyl...@gmail.com

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Jul 27, 2025, 11:39:24 AM7/27/25
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> If both primary and secondary fiducials are set to the same Z level, will this affect the accuracy of the 3D calibration?

Don't do that! The whole point of having two calibration fiducials is so that they can be at different Z levels. Most people adjust the focus of their cameras so that they have a sharp, in-focus image at the Z level of the PCB which is the Z level you should have your primary calibration fiducial located. The secondary calibration fiducial is typically mounted higher.  The higher the better as long as it doesn't cause any crashes and it is still reasonably visible in the camera view. Some out-of-focus is ok.

Mike Menci

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Jul 28, 2025, 6:02:01 AM7/28/25
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Rambo 
After  you have the down-looking camera on your machine and fixed to Z Head somewhere you need to turn camera lens (M12 lens) L or R in order to get the best view with sharpest image of your PCB (PCB is at Z= =mm ). Now you need to adjust camera settings and than you need to have  primary fid ( at Z=0mm level) and secondary fiducial (at  Z on +10 or +15mm ) in order to do camera calibration       

Rambo Jon

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Jul 31, 2025, 6:55:21 PM7/31/25
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Hello,
Thank you. This method worked for me, and I have now reached the milestones production phase. However, I don't know how to run my first task. I am working with the Eagle program. Can you provide me with any assistance?


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Mike Menci

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Aug 4, 2025, 3:10:08 AM8/4/25
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You can find instructions in OpenPnP here : https://github.com/openpnp/openpnp/wiki/Importing-Centroid-Data
Follow those! 

tonyl...@gmail.com

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Aug 4, 2025, 6:07:10 PM8/4/25
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I'd also suggest reading the User Manual - especially the Recommended Workflow and Running a Job sections.

Pierluigi Garaventa

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Aug 5, 2025, 6:43:38 AM8/5/25
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Hi,
 I found Opulo Setup Tutorial videos really useful to have a good introduction.


Pierluigi


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