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A modern 35mm film scanner for home

(www.soke.engineering)
251 points QiuChuck | 1 comments | 11 Nov 25 19:48 UTC | HN request time: 0s | source
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felixfurtak ◴[11 Nov 25 22:16 UTC] No.45893633[source]▶
RGB LED backlight is a terrible choice. Wide gamut but terrible color rendering.
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Brian-Puccio ◴[11 Nov 25 23:14 UTC] No.45894230[source]▶
Can I ask why it will produce terrible color rendering? In addition to commercial scanners that used narrowband trichromatic (RGB) light sources, hobbyists are creating their own RGB light sources to digitize color negative film claiming superior results and putting forward arguments why this is better:

https://jackw01.github.io/scanlight/

(NB: Most film I shoot is slide film, which I’ve been told doesn’t benefit from RGB light sources because it’s intended viewing was projected with a broad-spectrum white light [likely a warmer than daylight (but color temperature isn’t much of a concern for digitizing slides)] so I haven’t dug into this much.)

replies(2): >>45894777 #>>45895676 #
1. joshvm ◴[12 Nov 25 00:21 UTC] No.45894777[source]▶
RGB should be fine, especially if you use a genuine ultra-high CRI source. A few companies make them, I think Waveform is one of the more well-known. If you really want to spend money, the optics suppliers like ThorLabs sell broadband LED sources. In an ideal world you could calibrate the image sensor against a known spectrum so you'd know its response. If you can estimate colour to a reasonable degree then you can transform it to what it "should" look like. Nevermind that pixels are single-wavelength as well.

https://store.waveformlighting.com/collections/led-strips/pr...

Negative Supply use something similar in their light tables, though I don't know exactly what the source or spectrum is. They're highly regarded enough that I think it's not an issue.

You can also use LEDs for enlarging, but you need to be careful about buying the right bands for the paper. I've used Luxeon SunPlus with some success as you can buy the correct green/blue for the different contrast layers. Though for B&W, even a random 5500K module from Cree worked quite well.