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Film scanner based on a 3D printer

Posted by lyscanthrope 
Film scanner based on a 3D printer
March 17, 2016 04:59AM

I was having an idea yesterday and I am still in the stage of "is it worth it ?" so I wanted to talk about it. I want to build (one day when I'll found some time ...) a film scanner (as I shoot film).
Ok ... well ....that said, there are a lot of option to do it.

Usual design moves the film in front of the sensor (be it image or line) so I was heading toward that kind of design, but couldn't find something that was satisfactory (efficient yet simple). The I tought, I have a coreXY printer at home ... why not attach a camera on the head and make it shot severals time while scanning.
In the idea it is close to that one :[www.flickr.com] & [github.com]
but I would replace the dslr by a USB webcam or USB microscope (see below) to make the head lighter to move around.

So ...
Description of the idea :
- A core XY printer with a specific mount for a camera pointing down to the bed
- A light table on the bed
- Holders for film placed on the bed
- A PC hooked to the ramps and camera

Scanning operations after calibration (focus, exposure and geometry of the scanning space):
- Move the head to the new position (depending on the field of view) *
- Take a picture at a fixed exposure **
- Iterate

Well that's all for it.

The next part will be the post-processing:
- Invert all the pictures ***
- Stich all the pictures (with hugin for exemple) ****
- Adjust curves and usual stuff

Now the remarks :
* The key idea to use a already working printer is that all the electronic is ready (or easiliy accessible), it is already calibrated and all movement are just a gcode away !
** I think it is important to be able to set all the parameters of the camera manually ... Webcam are usually "difficult" to know before hand if we can do this. More on the camera later !
*** Inverting the pictures needs to have enough color depth to be usuable. It seems that most of them are 8bits ..
**** Stitching the pictures may be done out of the software. It will probably be a lot of small pictures.

Ok ... now the problematic points regarding the camera:
Sharpness : One don't want to scan outstanding images (when you manage get them winking smiley) with a filmsy lens of a cheap webcam. I see two solutions : use a high grade camera with a high macro quality lens ($$ and heavy) use a smaller sensor with a larger lens (so you stick to using the center of the lens which is usually sharper). I wanted to go toward c-mount (or CS) usb camera .... there are'nt a lot of them !! Any ideas ?
Depth of Field : Ideally we would want to shoot around f5.6 or F8 to have adequate image quality in case the film isn't flat (and it won't be)
Focus : Manual will be ok
Minimum focus : we don't want the minimum focus to be longer than 10cm (so we can fit a lighttable on th bed)
Color Depth : This is a serious problem, most of them does not allow to take RAW and only output JPEG ...
Exposure control : This is a major problem (as color depth) as I don't known how to be sure that a camera will work before hand
Resolution : Pretty hard to known the native (not interpolated) resolution of the camera ... but a low megapixel one should suit as we will stitch later on.

Regarding all that I was thinking at :
- A USB microscope like this one [www.adafruit.com] Probably the worst choice of optic !
- A C-mount USB camera like this one [qUAAOSwYHxWJLGW" target="_blank" rel="nofollow">www.ebay.com] with a C-mount lens -and perhaps an extension tube
- A CS-mount raspberry pi camera like this one [www.uctronics.com] but ....that would mean using a raspberry pi in the middle ...a lot less conveniant than directly connected to the PC

Well ....do you have any idea on other cameras that would be usable ?
I was planning to work in python for openCV and I guess we should be able to control the python using it.

Any remarks, idea or advice ?

Best reghards
Re: Film scanner based on a 3D printer
March 17, 2016 06:18AM
... what's wrong with a dedicated filmscanner?

You can find the "Primefilm 1800i filmscanner" at ebay for < USD30


Edited 1 time(s). Last edit at 03/17/2016 06:19AM by VDX.

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Re: Film scanner based on a 3D printer
March 17, 2016 06:33AM
Dedicated film scanners are great. I have a Pakon 135+ and I am totally happy with it scanning my 35mm. The color correction of the kodak software is fantastic.

But well, it is getting older and older. Its age in itself is not a problem ... the real problem is the spare parts that are no longer available and they are getting scarce.
Currently there are no other scanner that scan as fast as the pakon with the same quality (even if it is only 6MP per frame).
So I would like to anticipate its death winking smiley

The second point is that .... it only scans 35mm film. Medium format is nice too !

And last point ....building is fun isn't it ? smiling smiley
Re: Film scanner based on a 3D printer
March 17, 2016 06:36AM
... so then, happy building winking smiley smileys with beer

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Anonymous User
Re: Film scanner based on a 3D printer
March 23, 2016 08:32AM
What about a 3D printed better mouse trap ? thumbs up
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