Daniel Reetz, the founder of the DIY Book Scanner community, has recently started making videos of prototyping and shop tips. If you are tinkering with a book scanner (or any other project) in your home shop, these tips will come in handy. https://www.youtube.com/channel/UCn0gq8 ... g_8K1nfInQ

Soraa LED color temperature and flat top snap accessory

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ilmarmors
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Joined: 06 Jun 2015, 07:46
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Country: Latvia
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Soraa LED color temperature and flat top snap accessory

Post by ilmarmors » 13 Jul 2015, 12:18

I read that suggested high quality LEDs are Soraa 00919:
http://www.diybookscanner.org/archivist/?page_id=278

From manufacturer page:
Manufacturer reference ID: SM16-07-10D-927-03
Lamp description: Vivid 2700K 95CRI 7.5W 10 degree
Rated voltage: 12V
Rated power: 7.5W
Nominal CCT: 2700K

From Wikipedia about Color temperature incandescent lamps temperature range 2700K-3000K.

My questions about color temperature and even light distribution:

1. if camera supports setting exact color temperature, then everything is fine. What color temperature corresponds to incandescent / tungsten white balance in cameras where you can choose only type of white balance? Is the same Soraa LED but with color temperature 3000K is better in general case? Or not?

2. Can Soraa flat top 25x25 degree snap accessory be used instead of crossed lenticular lenses in standard Archivist? See: AC-FR-2525-00
Let me know, if you are interested to get F608ZZ, anti-reflective glass, QLV-1 MR16 GX5.3 socket holders or other Archivist components in Europe.

duerig
Posts: 368
Joined: 01 Jun 2014, 17:04
Number of books owned: 1000
Country: United States of America

Re: Soraa LED color temperature and flat top snap accessory

Post by duerig » 13 Jul 2015, 12:57

(1) If you use those SORAA bulbs, then the Tungsten white balance setting is what you want to use for your camera. It is possible that a custom white-balance setting might yield slightly better results, but I don't know of anybody who has explored this question yet. But you could get a camera color card and photograph it with different settings. In general, 3000K bulbs don't seem better than 2700K bulbs. Just pick bulbs with a known temperature and choose the corresponding white balance.

One issue with SORAA bulbs right now is that there is a manufacturing and/or shipping issue with their supply. As of a month ago, I simply could not get my hands on one. A good High-CRI substitute is Green Creative's 95350 bulb which works as a drop-in replacement: http://gc-lighting.com/wp-content/uploa ... gh-CRI.pdf

The SORAA bulbs might be more available now. But make sure to call the place you order from to check to see if they actually have them in stock before buying from a web form.

This leads to (2) where I think that the flat top snap accessories could potentially do the same job as the lenticular sheets. You would have to order them and try them out. But if you were to go that route in the Archivist, you would probably need to adjust or adapt the mounting plate on the top so that you could still secure them in place. I would try the widest beam if you were going to go down this route.

If you want to experiment with the snap lenses, I will be very interested in seeing the results. But if you are turning to the snap lenses only because the lenticulars seem hard to make or acquire, then PM me and I can get you some for pretty cheap. I have a box of them in my shop.

-D

liklev
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E-book readers owned: mobi, adobe de, kindle on android,moon reader
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Re: Soraa LED color temperature and flat top snap accessory

Post by liklev » 20 Sep 2015, 15:31

hi,
as i know all white LEDs (except RGB LEDs) using a blue or violet led as source then a mostly yellow-ish color resin dome converting the blue light to white. Very similar to fluorescence tubes where some ultra violet light is generated in the tube then the white dust (phosphore and other elements) covering the tube makes the conversion.
The spectral graphs of warm/neutral/natural/cold differs in how high the blue peak how deep the green/yellow valley then how high the red hill.
wanna say all white leds have the (RGB) content but in different proportions (google up spectral distribution white led).
If your camera has customizable white balance then you can try to compensate the color temperature of your light source. set it according your cam's user manual. (mostly you have to shoot a blank white paper occupies the full view of your cam under your present light condition)

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