Low distortion Lens for 23ux236

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Micr0
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Low distortion Lens for 23ux236

Post by Micr0 »

Low distortion Lens for 23ux236Quote 3dxcan
Sent: 17 Aug 2017, 02:17
by 3dxcan

Dear Micro,
To get over the scan accuracy over the entire field of view I'm still having problems, therefore i have to limit the resolution of the scanner (which will automatically crop the sides of scans). Could you suggest a low distortion lens that will give me good results without distortions that will align well and solves my problem.
I'm using Imaging source 23ux236 and currently a 12mm computar 1214MP2.
I looked up M1224-mpw2 which is a "ultra low distortion lens" but for a 1/1.8 lens, tge distortion factor in the datasheet Is aporox. The same as 1214mp2.
I'd appreciate if you suggest a good lens.

Thanks in advance.


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Re: Low distortion Lens for 23ux236
Sent: 17 Aug 2017, 22:00
by Micr0

Distortion is a very general term and there are many factors to a "good" lens. MTF is one of the important features when choosing a high resolution lens. Have a look at the Richo FL-BC1220-9M



____________________________________________________________________________
Re: Low distortion Lens for 23ux236
Sent: 17 Aug 2017, 22:00
3dxcan wrote:


I don't know much about technical details regarding lens distortion, but i very well know that professional scanners from GOM and solutionix utilize this lens from Schneider, please have a look at the lens Datasheet and see if this is any better than regular lenses used with David and let me know. it does include the graphs you talk about.

https://www.1stvision.com/lens/schneide ... 1.4-12.pdf

Thanks in Advance.
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Micr0
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Re: Low distortion Lens for 23ux236

Post by Micr0 »

Looking at that spec sheet that is a really nice lens. After a quick google search it seems to be very pricy at also almost $1100usd. So very expensive for a prime C mount lens. Goes to show you get what you pay for.

FWIW The one lens I really would like to try is the Zeiss Distagon. Again a $1k lens.
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mading
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Joined: 31 Jan 2017, 13:09

Re: Low distortion Lens for 23ux236

Post by mading »

http://m.ebay.it/itm/SCHNEIDER-KREUZNAC ... iid%253A25

Something like this for Is 23ux236 and acer k132?
LG PF50, LG PF1500, RangeVision DIY: 2x DahengMer630, 2X12 and 2X16 mm 5Mp ZK lenses, RV turntable
Curiousjeff
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Joined: 16 Nov 2016, 22:31

Re: Low distortion Lens for 23ux236

Post by Curiousjeff »

FWIW

I wonder about the need for a very good lens on the camera side (?)

Stepping down the lens will use the best part of the lens and increase depth of field ( as long as the stepping is within reason).

I find that a precise calibration board, a correct angle between camera and projector, good f-stop, minimal electrical interference and no vibrations are critical to a precise scan.

I have not noticed the alignment problem due to the lens itself.

A good lens will not doubt improve the scan quality if the camera has a high resolution chip.

On the other hand, I have encountered problems of alignment when I place a close-up lens in front of the projector. The distortion from cheap close-up lens is beyond what David can compensate for.

Jeff
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Micr0
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Re: Low distortion Lens for 23ux236

Post by Micr0 »

Curiousjeff wrote: 21 Aug 2017, 11:59 FWIW

I wonder about the need for a very good lens on the camera side (?)

Stepping down the lens will use the best part of the lens and increase depth of field ( as long as the stepping is within reason).

I find that a precise calibration board, a correct angle between camera and projector, good f-stop, minimal electrical interference and no vibrations are critical to a precise scan.

I have not noticed the alignment problem due to the lens itself.

A good lens will not doubt improve the scan quality if the camera has a high resolution chip.
I don't think a very expensive lense is necessary either. I have good lenses and where it helps most is in the depth of the scan envelope. That is the better lenses allow me to get accurate data from further from the center of the scan focus. It also make my setup needs less exacting.

On the other hand, I have encountered problems of alignment when I place a close-up lens in front of the projector. The distortion from cheap close-up lens is beyond what David can compensate for.

Jeff
close up lenses are crap. I'm experimenting with shimming the projectors lens to move it about 1mm further away from the image source in order to shorten it's focal length. So far it's worked great. However I accidentally damaged part of the projector motherboard and now the projector faults (over heat warning) after being on for only 3 min. This was an old Optoma and not my good projector incase you were wondering. I got an Acer K11 coming from ebay for <$100 and I'll try not to screw that one up. Ideally, once I know what I'm doing, I hope of make a frame that will allow me to have a projector with swappable lenses. I have a bit of a ways to go before I get to that point.
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3dxcan
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Joined: 02 Jun 2017, 17:21

Re: Low distortion Lens for 23ux236

Post by 3dxcan »

Curiousjeff wrote: 21 Aug 2017, 11:59 FWIW

I wonder about the need for a very good lens on the camera side (?)

Stepping down the lens will use the best part of the lens and increase depth of field ( as long as the stepping is within reason).

I find that a precise calibration board, a correct angle between camera and projector, good f-stop, minimal electrical interference and no vibrations are critical to a precise scan.

I have not noticed the alignment problem due to the lens itself.

A good lens will not doubt improve the scan quality if the camera has a high resolution chip.

On the other hand, I have encountered problems of alignment when I place a close-up lens in front of the projector. The distortion from cheap close-up lens is beyond what David can compensate for.

Jeff
What would be the optimum f-stop for computar 1214mp2,1614mp2 (12mm & 16mm) ? how do I know what aperture is optimum? wikipedia says : "three stops closed down from maximum aperture" that makes 16 as optimum aperture, but i feel that is too closed, and david suggest less than 16. the projector needs to be too bright to get the sine waves up bellow the top blue line. i even doubt ACER K132 can reach that level of brightness.
Curiousjeff
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Joined: 16 Nov 2016, 22:31

Re: Low distortion Lens for 23ux236

Post by Curiousjeff »

From what I understand, you are trying to figure out what is causing your alignment problems.

I would test at F-8 or F-11.

If the scene is too dark, push the gain up just to test. It will maybe give you bad surface but for the moment, you are trying to find where the distortion is coming from.

If using David 4, you need a precise panel, correct angle between camera and projector, correct f-stop, all settings in projector set to off.

Start by scanning an item that does not reach out to the edge of the image zone.

You must go step by step
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