Cameras not in the same focus plane?

[neveroddoreven]

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?

[24c]

Is this typical?

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

[propologist]

When free scanning what is the optimal distance ?

[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

[Hugues]

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

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.

[neveroddoreven]

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.

[24c]

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

[Hugues]

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...

[24c]

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

Mike

[Hugues]

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

Mike

That would be cool,
and because it's sunday and i'm a nice guy 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.