Camera setup aspect ratio

When calibrating camera alignment, the test card is much narrower than my bed (510x300).

I can get very low numbers when calibrating the lens, and get precise placement when doing the camera alignment (e.g. I’ll engrave some test marks at the corners of the test card and they’re spot-on <1mm)… but then when working on the edges of the bed I’m often off by several mm or more.

Is there something else I should be looking at first to solve this? Or am I right in assuming that it’s a limitation due to the size of the calibration?

Here’s an example of the results. The first shot shows how I’m engraving circles around the red spots:

And this photograph afterward shows how circles outside the test card area are mis-aligned (I’ve highlighted them w/ squiggly lines)

3 things:

  1. when doing lens calibration, are you using the fisheye setting? If your lens has any distortion at all you likely want to be using fisheye
  2. when you do the camera alignment, are you setting up the targets to fill as much of your bed as possible?
  3. Are you doing the camera alignment with distance from material to lens the same as when comparing measurements? Note that camera alignment will only be fully effective at one focal distance
  1. It’s definitely a very wide angle lens, but I don’t recall if that option was selected. I’m getting a new camera tomorrow (for unrelated reasons) so when I go to set it up I’ll double check that’s enabled.

  2. You can see in my second post it’s nearly filled. I may be able to eek out a few more cm.

  3. Approximately. To get the calibration image detected appropriately, I had to do the lens calibration with the lid open, holding the test card.

But to my root question… should I infer you don’t think the mis-matched aspect ratios are contributing to the problem?
And is there a way to tell lightburn to use a wider camera alignment 1-2-3-4 test card?

I hadn’t seen that before posting. I think what you’ve done is fine.

That’s not an issue. It’s the camera alignment where this will be very important.

No. This should be fine as it should discard the unused pixels.

No. As far as I know it relies on a square pattern at this point.

One thing you could try to do is to recapture the overlap, then use the shift/scale adjustments in Camera Control window to align the burn to your test circles. Then save the adjustments. That might get you the adjustment that you need.

Ok, thanks for taking the time to go through this with me. If I understand them correctly I don’t think the shift/scale will be helpful since it’s universal, whereas I need to apply adjustments to portions of the bed.

It’s a minor issue though since the bulk of my bed is well aligned. We’ll see how it goes after a new camera and redoing the alignment.

Thanks again.

It’s proportional so may still work. I’m guessing that the issue is actually not localized to one position but is gradual throughout the range. But double-check if that’s not right.

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