Yes, that’s correct. I was originally planning to replace my old RaLeno PLV-S192, but I ended up returning it because there was a problem with the product. In fact, the PLV-S192 worked perfectly well for scanning 4x5 color slides and black & white film, so I decided not to purchase the P260C again. Then I came across an article about a DIY lightbox, which piqued my curiosity. 
Thank you, I remember your rather wonderful micro-adjustable platform now! You might want to look at the information on the light box that Darrell Davis built if you haven’t seen it before, it’s over on the Negative Lab Pro FB forum, you have to join but that’s just a formality:
Because it’s FB it’s quite hard to find everything but he built the first one back in 2018 and then gathered enough interest to make a batch this year using the best components, particularly the LEDs.
I see that the information on his first version is over on the ‘Digitizing film with a digital camera’ FB forum.
He provides a lot of background information if you go back and seek it out.
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Can you please provide more details about these pieces and where they come from. Look very nice!
Thank you for the useful information!
I’ve been having problems accessing Facebook for the past few months. I have my own personal Facebook page, and I’ve been active in several forums there, but at some point I started having trouble with the verification process and have been unable to log in.
So, unfortunately, I can’t use Facebook at the moment.
I miss Facebook.. 
For the Z-axis manual linear translation stages, I used the LZ60. They are very inexpensive, but remarkably precise. They are also very well made. If you search around, you may be able to find an even cheaper supplier.
For the rails, you can find various options on AliExpress by searching for “Linear guide rail SGR.”
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Thanks a lot! Appreciate the pointers.
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I dug deeper just a little bit and got the following:
The violet shown compensates the mask of Kodak Safety Film 6014 when captured at +2 exposure, which is below any clipping. Screen (backlight) was set to about 100 cd/m2.
RGB Values are for sRGB, screen is an iMac’s that can do the values as shown.
With that background, scans are white balanced from the start and due to my camera set to UniWB, I can set exposure to +2. Different film stock has different masks, so this hue will not work the same in every case. But you’re free to test it with your stuff, using a colour managed tablet as a backlight.
Note that the colour shown by the forum software is slightly off.
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I have an app in Python which allows one to control the color of second screen/projector via sliders and even vingnetting across screen.
If anybody interested I can publish the source
Continuing with tests of my new scanning rig, i found the following:
With a 100mm lens on APS-C, the raster of an iPad backlight registered when the scan was taken at f/11, but not at f/8. Imaging ratio was about 1:2, which corresponds to a 645 repro on full frame.
Example at 300%
Conversion, straight out of NLP, of a 1970s negative scanned with “violet” (lavender) backlight.
From a colour point of view, NLP does a great job, considering how far this backlight is away from the recommended white, high CRI light. My point is not colour though. I try to minimise digital noise by pushing the backlight’s R and B channels up to the level of the R channel response to the orange mask. I think that the app proposed by @VladS above could help in the process.
I usually convert at very low pre-saturation and “Basic” colour model, here it was “Frontier”.
Here is the gifthub repository RGBGenerator/README.md at main · vsaddr-github/RGBGenerator · GitHub
The idea was to have true laser video projector shine light into integrating sphere with opening slightly bigger then film gate. The color sliders meant to create specifically colored light which would be fully compensating orange mask . The app has logging feature so you can experiment with colors and log the RGB values to reuse later. To find the exact RGB set compensating orange mask you use film leader where there is no image just mask. How to measure if mask is compensated I think you use some device which shows RGB peaks to be of same intensity. I know this is very vague definition - I am really not suggesting using thousand dollar spectrophotometer I use myself. The histogram in the camera set to 5500K is good approximation. Of course the whole exercise means no sprocket holes should be visible whatsoever.
Thanks for the link @VladS , I’ll check it out.
…enter UniWB!
UniWB is a custom white balance that gives all channels the same digital “amplification”.
In case of the Canon EOS cameras I use, the multipliers for GREEN are always 1024, the multipliers for RED and BLUE vary depending on white balance. Balancing a fully blown image with Custom WB gets me 1030, 1024, 1024, 1024 for R,G,G,B which means that R is 0.6% over target, easily good enough.
In order to keep things konsistent, the same camera settings (picture style, contrast etc.) should be used while getting the custom WB and using it. Then, all data goes through the same processing and the histogram will show, when the mask is compensated. The lavender I posted above gets me there for the Kodak 6014 (Kodakolor II) most of my negatives are on. Different film stock will probably need different backlight colour.
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