# Lightburn camera issue2

Alright guys so i was able to get my camera up and running and its working but im finiding an issue where the job isnt perfectly alighted (a few mm high) ill attach photos for reference

Please let me know what i can do to improve my situation. Thank you in advance

Thatâ€™s really interesting. How thick is the work-piece?

Iâ€™m wondering if the height of the work from the bed changes the angle enough to change the modelled location.

If you have time to experiment - please cut a paper rectangle the size of the workpiece and put it in your engraver and set up the job exactly like you did last time. then generate the preview picture like you did above.

Then place the workpiece exactly on the piece of paper to see if a location error is introduced.

With all the math involved in the camera calibration a material thickness vs location offset tool doesnâ€™t seem too far from impossible.

Dying of curiosity!! let me know.

Man thats a great idea! Thank you the alignment was done for the thickness of a piece of paper and the bed was lowered to fit the piece of wood. The hight from the laser head is still the same but the depth of the bed is deeper then when i did my alignment. Do you know of a way to compensate for that?

From my understanding the camera is setup for the table level. The distance to the object should be at the level you set it up. Put a 2 foot cube in there and the top is where the table top was, it should work ok.

The table position doesnâ€™t matter after calibration, the machine has no way to know where the table isâ€¦

At least thatâ€™s my understandingâ€¦

If you lined up your X,Y with a sheet of paper on the bed at the focal height and then lowered the bed by the material thickness then the image should land on the top of the work-piece, in the focal work plane as predicted.

If you lined up the image of the X,Y with the top face of the tall work-piece, and then lowered the bed to focus it, the top of the thick work-piece would be off by (what i believe to be) the cosine error .

If you lined up the image of the XY with the dropped bed and put the tall work piece on it, the error would be introduced the other way.

What did you do?

â€śIf you lined up your X,Y with a sheet of paper on the bed at the focal height and then lowered the bed by the material thickness then the image should land on the top of the work-piece, in the focal work plane as predictedâ€ť
This was the case, i might not of lowered the bed enough then as i tend to lower the bed to the hight of the material then i raise up the bed by .2mm so i will try again tonight and see if it works as i intended! Thank you for your help guys!

The overlay also looks very out of focus. You may need to correct the focus and rerun calibration and alignment.

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I didnâ€™t even think of how the (auto?) focus might change magnification and introduce a location error. I love the information density.

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