Sometimes I need to photograph (Canon a630) a document, if it's too big or 3D to fit my a4 scanner.

It's difficult to get the lighting perfectly uniform.

Alternatively, sometimes a book is too precious to "press down flat" for photographing, which means even under uniform lighting, the image is non uniform, since the presentation angle of book to light isn't constant (e.g. near the spine)

Can anyone recommend ways to correct this? (it would be possible, if needed to take a reference shot of a pure white piece of paper)

(and should I start another thread for stains on documents e.g. oil stains on engineering catalogues?)

BugBear

To quickly check for uniform lighting I hold a ruler on edge in the middle of the field and the shadows on both sides should be of equal darkness.

For books, arrange it so that the lights are coming from the top and bottom of the page, (even of course) and do one page at a time. Sometimes you might need a helper or devise some way to hold the other page in an almost vertical position so the page you want will lay flat. Make sure the vertical page does not cast a shadow on the other page.

As far as the oil stains, are the originals black and white or color?

BugBear, long focal length lenses compress persective so you shhould get better results taking the photo from further back with a telephoto lens and strong light so that you have adequate depth of field. A white piece of paper to the side is always useful to apply a curve or levels adj to bring the color balance back in line as most indoor lighting adds a color cast of some type.
As for the oil stains, I would start a new thread and attach a sample image.
Regards, Murray

To quickly check for uniform lighting I hold a ruler on edge in the middle of the field and the shadows on both sides should be of equal darkness.

For books, arrange it so that the lights are coming from the top and bottom of the page, (even of course) and do one page at a time.

Yes, I do all this WHEN possible; my question was how to correct why it's not.


Sometimes you might need a helper or devise some way to hold the other page in an almost vertical position so the page you want will lay flat. Make sure the vertical page does not cast a shadow on the other page.

(Greta Garbo voice)I work alone...(end voice)

As far as the oil stains, are the originals black and white or color?

Mainly black and white (due to age) but some 1960's catalogues.

BugBear