What I learned about Lighting from setting up a copystand

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Re: What I learned about Lighting from setting up a copystand

Postby daniel_reetz » 04 Jan 2010, 12:40

When the actual pictures go online, there will be exif. In this case, there is no exif because all these images were created as new .PSDs in Photoshop.

The relevant camera settings were:
zoom: 114mm, which stuck me with
aperture:f/4.9 (this is effective, not physical, the A95 doesn't have a real "aperture", just an ND filter as far as I know)
shutter 1/60sec
iso 50 (the base ISO of the A95)
autofocus set to center (I held the button half-pressed between shots for rapid shooting)
WB set to Tungsten
JPG at highest quality and resolution
zoom at full

I ignored the in-camera metering and instead checked the images on the computer. It claimed that these images were 1/2 stop underexposed, but checking the pixel values in Photoshop let me see that the red channel was clipping even at 1/3 under.
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Re: What I learned about Lighting from setting up a copystand

Postby phaedrus » 04 Jan 2010, 15:25

I'm impressed with the healthy-looking mean Dan, dunno about what's in that bowl you're eyeing up though - doesn't seem all that edible to me :mrgreen:

Some good thoughts there, I assume the camera covers you showed in an ealier post would also assist. I've purchased some high-freq ('cool') CF's to try out and have been very pleased with the results on a 'normal' text & grey-scale photo book (a family history). The images were significantly cleaner than with a tungsten or 'warm' CF with the camera on auto. Of course it may mess things up for colour but in my case there's very little of that in what I'm doing. Ann, I wonder if you've tried anything other than than the 'sunlight' frequency and if so what results you had? Apologies if you've already posted that info somewhere but I couldn't find anything in the quick look I had.

Cheers, P.
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Re: What I learned about Lighting from setting up a copystand

Postby Misty » 04 Jan 2010, 16:51

The standard for professional digitization is D50 (roughly 5000K), which is a "horizon" daylight. I'm not sure if there are any inexpensive home-targeted lights at that temperature.

Edit: It does look like there are. I believe D50 is a bit warmer than many "daylight" marketed lights (which target the cooler 6500K).
The opinions expressed in this post are my own and do not necessarily represent those of the Canadian Museum for Human Rights.
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Re: What I learned about Lighting from setting up a copystand

Postby daniel_reetz » 05 Jan 2010, 06:43

Misty, for whatever reason I'm thinking about fluorescents again, about their spiky spectra, and so on. Some semesters ago I took a color science course which discussed the resulting problems of metamerism, mismatched sources and detectors, and so on. I suppose the conservation community has their own angle on this, and I'd like to read what they have to say. Writing all that just to ask: are you aware of any conservation "best practices" worksheets or journal articles on the problems/advantages of fluorescent lighting in this context?
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Re: What I learned about Lighting from setting up a copystand

Postby Misty » 05 Jan 2010, 11:53

I haven't seen papers discussing those problems specifically, unfortunately. Most of the digitization standards and best practices sheets I've read don't go into that level of detail on lighting selection.

Fluorescents are the common choice for the purposes of protecting the materials - they're commonly available in no-UV versions and pose no heat gain issues, unlike tungsten-halogens, incandescents, or sunlight. For digitization in an archival context, protecting the materials is usually the first concern - scan quality comes after that. That's where fluorescent's biggest advantage is (aside from their ease of availability). As an example, see chapter 3 of the Canadian Council of Archives's Red Book.
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Re: What I learned about Lighting from setting up a copystand

Postby daniel_reetz » 06 Jan 2010, 12:19

Not that it particularly matters, but today while searching through some of my images, I found a better shot of the copystand in its entirety. It's a Polaroid MP-4.
IMG_1491.jpg
IMG_1491.jpg (118.98 KiB) Viewed 1348 times

This picture was taken just days before I created my first book scanner with it.
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