Page lighting, exposure, etc.

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Re: Page lighting, exposure, etc.

Postby JDSimmons » 02 Aug 2010, 08:01

Agreed. I hadn't figured out how to use White Balance on my Kodak camera when I did my first book and half the pages came out brownish. By the time I used Scan Tailor on them you couldn't tell. I do need to do color scans, however, so for now I'll use the Tungsten bulbs for that purpose only. I don't scan enough books for the electricity savings to be meaningful.
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Re: Page lighting, exposure, etc.

Postby univurshul » 02 Aug 2010, 11:35

JDSimmons wrote:Agreed....By the time I used Scan Tailor on them you couldn't tell. I do need to do color scans, however, so for now I'll use the Tungsten bulbs for that purpose only. I don't scan enough books for the electricity savings to be meaningful.


On my first two rigs I used 2x150watt halogen bulbs less that 36" away from the platen for my color image transcription (48" distance for XL books); these get hot, almost too hot. Since testing CFLs and now going to LEDs, I really appreciate the cool-operation aspects; standing there for extended periods and scanning under halogen heat is annoying. With new tech bulbs, I can leave the LED lights on and let them light the room, without powering down, turning on other lights, etc. I guess the convenience aspects are really spoiling me now.

If you live in a cold climate/winter time scanning with incandescents has a purpose I guess!
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Re: Page lighting, exposure, etc.

Postby iwenttoofast » 08 Aug 2010, 14:01

Just to add a few hopefully interesting observations to this thread:

White balance is indeed the setting upon which you want to focus. Essentially, it controls whether the "whites" coming from your camera lean towards yellow / orange ("tungsten", or lower color temperature settings), or blue (fluorescent, or higher color temperatures). But playing with it is the only way to learn what it does: learn what settings on your camera make the pages look more blue, and which ones make them more yellow / orange. Eventually, you'll find something that works. But that's all white balance really does.

First off: unless you're actually using a color-managed workflow, which is extreme overkill unless you're doing true preservation-quality imaging or something like advertising work where the colors in a corporate logo need to be exact, there's no "right" answer. Just tweaking the white balance (and other settings) until the page color looks the most accurate to you, is the way to go. Also, be sure to compare it on different monitors: it'll look a little different on every one (unless of course, you've profiled them using the rather expensive required software, which again is usually unnecessary). But if it looks good to you, go with it.

However, page-to-page color consistency is perhaps something to strive for. It's already been suggested to turn off all of the "auto" settings like auto white balance, auto exposure, etc. The problem with these "auto" settings is that they're constantly moving around, so you might start with neutral pages and end up woth something more blue because the camera "thinks" that's better. Once you find a setting that works, try to lock it down. Also, try to minimize the amount of extraneous light in your scanning environment. That's why you see the black hoods on top of the Scribe and ATIZ units. And staying away from unshaded windows etc. is definitely important. Daylight is highly variable, and the consistency of your scans will suffer. We kill the overhead room lights when we're scanning, too.

We shoot under a pair of off-angle fluroescent softboxes, with diffusors, that are far enough away to minimize glare and hotspotting. They are around 5500K color temperature, I think, and they work pretty well. I wish they were smaller and more durable, but those types of units are very expensive.

-- Jim
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