Cameras not in the same focus plane?

I noticed that my scanner cameras are not in the same focus. I took a white product box and stood it up on the turntable facing squarely at the front of the scanner, with the scanner on the included plastic stand, and the equipment lined up on the transluscent guide sheet. The product box served as a focus plane, and was packed with lines of crisply printed sans serif characters each roughly 2mm high.

The camera nearest the scanner USB port is focused most sharply at the furthest plane along the second-to-outermost ring, while the other camera is most sharply focused at the nearest plane along the same ring. In either plane, the least focused camera sees blurred typeface (you can make out what it reads but it looks terrible).

Is this typical?

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Is this typical?

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In my experience it is.
What I look for is the black & white unphase screens to be crisp. These patterns are important for defining the surface detail. If they aren't I recalibrate, and then use a piece of white paper to establish the distance, and move the scanned object into this focal zone. That definitely appears to improve things for me, but I am free scanning.

Mike

When free scanning what is the optimal distance ?

I found it was 430mm for me, or thereabouts, and it's whatever distance the projected unphase mask screens stay crisp over the object.
I don't know if this is all part of the calibration process re the test piece on the turntable
I haven't got the experience of Nerv, but I quickly found if I was too far away, the representation of surface detail or the perceived scan quality dropped off considerably.

Mike

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Originally Posted by 24c

I found it was 430mm for me, or thereabouts, and it's whatever distance the projected unphase mask screens stay crisp over the object.
I don't know if this is all part of the calibration process re the test piece on the turntable
I haven't got the experience of Nerv, but I quickly found if I was too far away, the representation of surface detail or the perceived scan quality dropped off considerably.

Mike

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Sorry, What is the projected unphase mask screen ??

Are you referring to the black cross that is projected in free scan mode ? For me this cross is in focus at 50cm.

I think 24c refers to the fine dot pattern that shows up only at a certain distance. It's a super fine hexagonal dot pattern and sparkles a bit. Looks like micro perforations, they are so fine.

Sorry Hugues, I thought that's what the patterns were called in white light scanning :?

Do a test scan and wait for the black and white vertical stripes to show up when the scan is running, these varying in width. when I did my first free scan I was too far away, and these had "fuzzy" edges. Although the scan info (shape) was OK, the texture wasn't right. The casting looked melted, but as soon as I moved it closer to the calibration distance, things improved. I then started to move the scanner closer to get detail further inside the object (hollow casting), once I got the external shape defined.
It worked a lot better for me this way, but I haven't done a lot with it since, as I need to make an articulating boom and fit a permanent Mini Arca quick release adaptor to the base of the scanner.

neveroddoreven, I haven't seen that pattern, but haven't been looking, but then I never seen the cross yet either! :)

Mike

Ok, so we speak about the black & white stripes.

I haven't checked their focus distance yet, but in theory they should have the same focus distance as the black cross, which you don't see ?!?! Do you disconnect the turntable in free scan ?

Shining 3d confirmed the scan distance should be 42-43 cm, but why have they set the focus distance of the cross at 50cm, that puzzles me. Unless you guys have it at 43 also and something is wrong with my scanner...

Hugues,
My focus distance for the black & white vertical lines is about 43cm, definitely not 50cm like your black cross.
My scanner and turntable are wired up via USB sockets in the wall at the other side of the room. I haven't disconnected the turntable in Free-scan, I just select the option on screen!
That might explain it then. :D
Just updating Parallels and then I will test what distance my black cross is in focus.

Mike

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Originally Posted by 24c

Hugues,
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Just updating Parallels and then I will test what distance my black cross is in focus.

Mike

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That would be cool,
and because it's sunday and i'm a nice guy :D you're going to do the plane test too , right ? LOL
I'm still discussing this curled corners issue with Eric from Shining 3d, really need to know if it's only my scanner doing this.
Just point your scanner at any flat surface, using 43 cm distance, and check in their software if the resulting scan has curled corners.

OK Hugues, just seen your latest response, and updated Parallels (eSATA drive fix, which I'm booting from)
I saw the cross!!
I looked at the focussing distance, and it's 43cm, so it's the same as what I found out with the white paper and the masks. 8)
At this point there is a slight zigzag, or pixelation to the horizontal line evident, and I'd have to say there is something slightly wrong with your set up.

It is Sunday, and I'll just flip out of OS X and do a test scan now. Only flat thing I have got is an iPhone 6!

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Originally Posted by 24c

OK Hugues, just seen your latest response, and updated Parallels (eSATA drive fix, which I'm booting from)
I saw the cross!!
I looked at the focussing distance, and it's 43cm, so it's the same as what I found out with the white paper and the masks. 8)
At this point there is a slight zigzag, or pixelation to the horizontal line evident, and I'd have to say there is something slightly wrong with your set up.

It is Sunday, and I'll just flip out of OS X and do a test scan now. Only flat thing I have got is an iPhone 6!

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So now i'm starting to get some elements to discuss with Eric. How's that my cross is sharp at 50cm !?

Only flat thing is your iphone 6 ? Don't you have walls and a floor where you live ? LOL, mind you, with the price of the iphone 6, you probably had to part out with your house LOL,

Would appreciate if you can post your plane test here, that would really settle it for me.

Hugues,
I was just looking for a flat object, so thinking glass.
BTW, I live in a mud hut, so the walls aren't flat. :P
Anyway tried an Apple SuperDrive, but this happened, and that was after recalibrating.
Attachment 7360

Mike

Ok,
Are the corners curled if you look at it sideways ?
You should look at it sideways before meshing, right after the scan is finished, easier to see.

Hugues,
No my corners aren't curled the whole thing looks pretty flat, but it got confused by the object on the turntable. If they have symmetry or similar features the alignment per turntable step gets confused.

Attachment 7364 Attachment 7365

Mike

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Originally Posted by 24c

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I looked at the focussing distance, and it's 43cm, so it's the same as what I found out with the white paper and the masks. 8)
At this point there is a slight zigzag, or pixelation to the horizontal line evident, and I'd have to say there is something slightly wrong with your set up.
...

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Found out today that my projector focus was at 50 cm because the front lens was probably not set right.

There are 2 tiny holes on the ring of the projector lens, i carefully rotated the lens counter-clock wise for a few degrees only and i could bring the focus back to 42-43 cm, which is the focus of the cameras it seems. So now my cross is focus at 42-43 cm.

I did a re-calibration with this and re-scanned, i think i have sharper details, but not 100% sure.

The sad thing though is that my left corners are still curled.

But anyway.