Compensating For Low Light Conditions

Question

As a photography newbie, I am hoping to use a book stand and dslr camera for occasionally scanning a few pages out of a Math book. Expected distance from camera to page will probably be about 18 inches. I am concerned about low light conditions, indoors.

Using an old, somewhat defective Kodak EasyShare P712, I experimented with a cluster of 4 inexpensive (60 watt) lamps around the page and found that the generated light wasn't bright enough. By somewhat defective I mean that the internal flash unit didn't seem to be creating enough light. For what it's worth, the camera has other problems, so I will be buying a new one.

When I research buying a new dslr camera, how do I research flash attachments? Does the attachment need to be part of the camera, or can I simply purchase 1 to 4 lamps that create very bright light? If I go with the external lamps, how many lamps should I use, and what type of bulb (e.g. wattage) should be used?

It will help me to learn if you could include links to (generic) sample products that will provide a solution. The idea here is not that you are recommending a specific lamp, camera, or flash attachment. Instead, the idea is that you are providing an example for me to read about, of the type of equipment that you are referring to.

I would like to strike a balance between budget and clarity. I plan to use a usb cable to transfer the pictures to my harddisk and then use pdflatex to embed the pictures in a private Math notebook that I keep as a pdf file. No one else will be examining the pdf file. The images simply need to be clearly legible to me.

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For what it's worth, before posting, I searched on this forum for "low light conditions", and found this article, most of which I did not understand. I infer from the article that achieving the right lighting will simply be one step, and that I will need to also research/experiment with specifying the right parameters for the photograph. However, I am taking the research one step at a time.

Answer 1

As long as you hold the camera and subject still you can use a long exposure to get enough light. Any DSLR or mirrorless camera should make that possible. I would use aperture priority at about f/8 and ISO 100, then let the camera meter set the exposure time. If the light is low it may be some seconds, but that is OK. Depending on your mount it may be useful to not disturb the camera when you press the shutter. You can use a remote release or an app on a phone to do that. A tripod will make getting the camera aligned to the subject easier than a book stand.

Answer 2

Kodak EasyShare P712 contains a 5.8 x 4.3 mm sensor with a crop factor of 6.

Usually DSLRs start from crop factor 1.6 (APS-C) or 1.5 and you can move all the way to crop factor 1 (full frame) and beyond (medium format).

The ability to collect light is inversely proportional to crop factor squared. This means even a basic DSLR collects 14 times more light than the Kodak EasyShare.

Your experiments with the Kodak don't mean anything, it's an extraordinarily poor camera in collecting light. It will create noisy or shaken images (the image stabilizer in that Kodak has only 2 stops of benefit).

I'm sure than four 60-watt bulbs, even if incandescent or halogen, will produce enough light near the page. Worst case is that the image stabilizer in the DSLR lens has to provide a stop or two or extra benefit but I'm sure it can in this case.

It's true that it's very dark indoors even if you think you have lot of light, but that mainly applies to moving subjects. Stationary subjects will be taken care of by image stabilizer.

Four 60-watt bulbs near the page you're photographing is plenty of light. Four 60-watt bulbs on the ceiling of the room aren't enough to photograph fast action in that room, though.

Answer 3

I have the feeling that it is not about low light. It is about you using an automated setting.

The pages of the book, I am assuming are white. And by low light, I am assuming they are gray in the photo.

If you are actually letting your camera (or any camera for that matter) take the decision about the exposure it will render any white paper page, gray.

What you need to do is compensate, either taking that reading as a base and manually adding one or two steps of light or setting the camera to overexpose by one or two steps.