I want to make a copy stand large enough for 16x20 glossy prints. I tried using an easel and two lights at 45 degrees, which seems to be normal practice, but I couldn't find a way to avoid reflections. I guess this is a lighting question as much as anything else.
Does anyone know a good resource for this stuff, or have some advice to help me?
The lens should just barely see through a hole in a relatively large flat panel. The surface of the panel facing the subject should be flat black. This eliminates most of the reflections that would otherwise spoil the result. One way to do this is to cover the front of the panel with a black fabric like felt or velour. 45º cross illumination is usually best. You can use a polarizer with the axis of polarization set vertical relative to the view screen (top to bottom). The photography should be done in a fully dark room. If possible, the walls and ceilings should be as far as practical from the setup so as not to reflect unpolarized light into the scene.
Then you can use polarizing screens over each of the lights with their axes set to match that of the lens polarizer. Using a polarizer on the lens combined with polarizing screens over the lights in this manner is called “cross polarizing.” It’s standard in copying artwork, such as paintings. I used to do a lot of this. It’s covered in the Kodak book “Copying and Duplicating in Black and White and Color.”
The lens should just barely see through a hole in a relatively large flat panel. The surface of the panel facing the subject should be flat black. This eliminates most of the reflections that would otherwise spoil the result. One way to do this is to cover the front of the panel with a black fabric like felt or velour. 45º cross illumination is usually best. You can use a polarizer with the axis of polarization set vertical relative to the view screen (top to bottom). The photography should be done in a fully dark room. If possible, the walls and ceilings should be as far as practical from the setup so as not to reflect unpolarized light into the scene.
Then you can use polarizing screens over each of the lights with their axes set to match that of the lens polarizer. Using a polarizer on the lens combined with polarizing screens over the lights in this manner is called “cross polarizing.” It’s standard in copying artwork, such as paintings. I used to do a lot of this. It’s covered in the Kodak book “Copying and Duplicating in Black and White and Color.”
What Ian C said. I had a project of copying family photos, all kinds of surfaces including glass framed photos. I think I got the polarizing lighting gels from Freestyle. It worked perfectly once aligned.
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One trick I used when setting up a copy stand and lights was to put a mirror, the same size as the max copy size, then move the camera so the mirror fills the viewfinder and then see can I see the lights in the mirror. (I hope I have described it correctly)
Another tip to assure even lighting: take something thin and straight, like a chopstick, and hold it perpendicular to the copy board, aligned with the lens axis. The shadows on either side should be lined up, the same length and intensity.
It was a fairly basic setup: two continuous lights at 45 degrees (see sketch). I looked for but couldn't see any reflections from the lights, but when I developed the negative there were two distinct hotspots, roughly where the second sketch shows them. My next purchase will be some polarising gels
Another tip to assure even lighting: take something thin and straight, like a chopstick, and hold it perpendicular to the copy board, aligned with the lens axis. The shadows on either side should be lined up, the same length and intensity.
One trick I used when setting up a copy stand and lights was to put a mirror, the same size as the max copy size, then move the camera so the mirror fills the viewfinder and then see can I see the lights in the mirror. (I hope I have described it correctly)
It was a fairly basic setup: two continuous lights at 45 degrees (see sketch). I looked for but couldn't see any reflections from the lights, but when I developed the negative there were two distinct hotspots, roughly where the second sketch shows them. My next purchase will be some polarising gels View attachment 355612 View attachment 355613
If your drawing shows more or less the actual setup, you are bound to have these hotspots; see below. Replace the print by a mirror (actually or by thought); does the camera "see" the lights in the mirror? You should move the lights more to the side, but no so much that the center of the artwork is under-illuminated. E.g., ove each light out far enough that it is at 45°, not from the center of the artwork, but from the nearest edge. Once that condition is met, and only then, the baffling recommended by IanC will be effective to remove specular reflection from behind the camera (ceiling or wall, depending on your setup).