Photographing Older Documents

I've taken pictures of documents recently. While in my case there was no requirement to have high quality pictures, I decided to try to aim for the most detailed and noise free pictures possible. To get the most detail, you should use the largest focal length available and take pictures from as close as possible, but such that you can still focus on the document. The F-number should be chosen somewhere between 6 and 8, this is where the lens will be the sharpest. Also, you may get distortions at the edges of the picture and this will be less of a problem if you shoot at F/7 instead of F/2.8.

In my case, I put my camera on a tripod with the legs fully retracted which puts the camera about 60 cm above the document. The focal length I used was 50 mm. Then, I first took a picture of a white paper to set the white balance. I then took one picture of the document to get the exposure right (with ISO set at the lowest setting, 100 in my case). You want to "expose to the right", so you check the histogram adjust the exposure to expose for longer but such that you don't get overexposed parts.

Then I started to take pictures with the remote control and manual focus where I focused on a few different parts of the page. And for each focus setting I took 5 pictures. Noise reduction was set to the lowest setting. Then when I was done taking all the pictures of all the pages in this way I downloaded the raw files to my computer and used the raw converter to generate 16 bit TIFF files, here the noise reduction was set to off. I aligned each set of 5 pictures and averaged over them to get rid of the noise. This prevents the loss of detail. Then the averaged pictures for the different focus settings were aligned and a focus stacking was performed.

The alignment of the 5 pictures was done using the align_image_stack program which is part of the free of charge Hugin panorama stitcher. After installing, you can just put a few copies of the program align_image_stack.exe in a few directories. Then in one of these directories you can open a command prompt and give the command:

align_image_stack -a al -C -t 0.3 -c 20 image1.tif image2.tif image3.tif image4.tif image5.tif

Here the -a al defines "al" as the prefix for the remapped images; -C means that these images will be cropped to the same size; -t 0.3 sets the tolerance for misalignment of the control points to be less than 0.3 pixels; -c 20 sets the number of control points to be 20 in the different segments that the program uses (in practice this means that you'll end up with many hundreds of control points).

The output is are then TIFF files named al0000.tif, al0001.tif, etc.

The next step is to average over these 5 images. I use the ImageMagick program for that. You can give the command:

convert al*.tif -poly "0.2,1,0.2,1,0.2,1,0.2,1,0.2,1" av.tif

Here the -poly command evaluates a polynomial, the 0.2's are the weights of each of the pictures, the 1's are the powers that obviously need to be set equal to 1 here.

The average of the pictures is then contained in the file av.tif, and this will be an extremely low noise picture.

Then aligning the different pictures for different focus settings must be done differently. First you must crop all the different averages to the same size, otherwise the align_image_stack program will give an error message. The command you then give is as follows:

align_image_stack -a al -t 0.3 -c 20 -m -z av2.tif av3.tif av4.tif av5.tif av6.tif av7.tif av8.tif ...

So, you now don't have the -C option, because we don't need to crop the remapped images to the same size. The -m option will optimize for the field of view of the images, this is necessary because of the different focus setting. The -z option will optimize for the distance of the camera to the object, this option may also be necessary to get good alignment.

Then you use the enfuse program that also comes as part of the Hugin program to process the focus stack. Move the aligned averaged files to some directory where you also put a copy of the enfuse program. There you open a command prompt and give the command:

enfuse --exposure-weight=0 --saturation-weight=0 --contrast-weight=1 --hard-mask *.tif

The output will be a file named a.tif

To save time with running the align_image_stack program, you can open multiple command prompts and process many sets simultaneously. On a 4 core processor you can run 4 instances of the program and speed up things by a factor of 4.

I was very satisfied with the results, the pictures were extremely sharp without any noise. The extremely small delicate details were visible just as well as on the original when using a magnifying glass.

To conclude, let me summarize the essential points:

• Take pictures from up close using a tripod and remote control. Use a long focal length to capture as much detail as possible.
• Use the optimal F-number for lens sharpness (typically somewhere between F/6 to F/8), do not increase the F-number beyond this range to try to get the entire document in focus, as that would decrease the sharpness due to diffraction. Instead use focus stacking.
• Use the lowest ISO setting, use the lowest noise reduction setting, but do enable long exposure noise reduction. The latter option lets the camera do a dark frame subtraction which eliminates the effect of hot pixels.
• Expose to the right and take multiple pictures. An exposure compensation of 2 stops and taking 5 pictures means that you'll capture 20 times as much light, as a result the noise can then be reduced by a factor of sqrt(20), about 4.5 times by averaging.
• Process the pictures as described above. Make sure the noise reduction in the raw processor is off.

My 2 cents.

1) Use the longest focal range you can, the longest lens and/or the furthest distance you can setup.

This is to reduce perspective distortion and chromatic aberrations.

2) You can construct a "table" made of MDF or something similar. You can set it at an angle so you can be far away with your camera but at the same time the document stays in place with gravity alone.

3) Use big diffuse lights, like 2 softboxes placed on each side of your camera to cancel each others' shadows.

Normally if you have a reflective surface you can't put them very close to your camera, because it would make hotspots, but as the old paper is matte, you can try.

Experiment with the distances and angles to achieve the most uniform light.

Don't use hard light. Don't put it near the plane of the document because you will make the shadows of the wrinkles of the paper more evident.

4) You can try flashes or fluorescent lamps. Try using an exposure meter to maintain uniform light across different sessions. If you are using fluorescent lamps use a neutral gray card to read and balance the light.

If color is important, use flash, not fluorescent. But I am guessing all newspapers are black and white and will be color corrected to remove the old paper look, to some extent at least.

Check your histogram and try to put it in the middle of the graph (Using the graycard). That way you have the most room to adjust it in post.

5) Try to use f/8 to maximize sharpness.

6) Use the camera's timer to reduce shake.

You might check with any local university archives, historical societies, or libraries with historical documents for advice. You might also check with any local hobbyist photography groups in the area. There might be someone who can walk you through the first few photos then set you loose.

You get good at photography by taking lots of photos, it's a simple as that. As you take more photos you develop an understanding of ISO, aperture, f-stop, focal length, composition, color, and sensor size. There isn't really a book that can teach you this although they can act as a guide as you improve. Even with lots of experience a photographer will discard a lot of photos for each one that's worth keeping. Bad photos teach you more about photography than good photos do and the more bad photos you take the better you'll get. That's just the way it is and there are no shortcuts.

There's also a good chance that a flash won't do anything to the documents. The risk from light is exposure to UV but as this article points out, there's little UV light coming from a flash.

If you are going to shoot this in low light you should definitely use a tripod, anything that will hold the camera stable and not let it move, slip or wobble. One from walmart or target would do or any photography shop. Point the camera so that the lens is perpendicular to the page (it sounds like it would be pointing down at an angle towards the documents), and zoom all the way in to 42mm (I'm assuming that you're using the 14-42mm Lumix f/3.5-5.6 kit lens). Use aperture mode (A on the dial) and set the aperture to f6 or f8, and then the duration of the shot will be set automatically. If it is dark then the time of the exposure will probably be pretty long, at least a few seconds, that's why you need a stable tripod that doesn't move. Also set the ISO as low as you can. ISO 100 might work but if it's too dark then the camera won't take a photo if the exposure is longer than the camera allows. Just bump up the ISO until it will take a photo. If you can get a cable shutter release then use one but you can also set an in-camera timer. That will cut down on vibration and get a crisper image.

As a test you might try setting up similar conditions at home and try photographing something like a magazine on a stand in low light. Once you've got a good image from doing that then you can go to work on the historical documents.

Your camera manual is your best friend too. Read up on aperture, manual, timed exposure, ISO, etc.... Don't use auto mode even though it's tempting.

For software you don't need photoshop. Apple has a program called Photos, they used to have iPhoto and older Mac's will still have that option. I'm sure Windows has something comparable. Photoshop is for heavy duty photo editing, you're just trying to make a few tweaks.

Other answers are generally good.
This is intended to be complementary.

I photographed old but not ancient documents (1900 on) in a library. These were for a church 100 year anniversary so quality had to be good but not utterly archival. For practical purposes the results were indistinguishable from originals by mere mortals.

I could set up equipment in a quiet corner but flash was not a good idea.
Extra lighting was possible but library fluorescents proved to be an acceptably good diffuse source with adequate exposure time. Tripod or similar essentially mandatory. Manually control all settings and focus.

I had documents flat with camera directly above.

Set camera to optimise results. Using max focal length possible (not vast with tripod) and range and choice of best aperture allowed very acceptable focus depth for this task.

If documents are consistent size cropping can be minimised. Use of an alignment guide allows documents to be placed consistently.
DSLR with preview helps but not essential.

Colour balance set by experiment for best results.
Use of in camera tools for WB setting helps but ultimately "how does this look" is best user fine tuned.

End results were "very good".

I've seen a piece of equipment that helps work around the problem of having to open the books flat. It was pretty fancy but you might be able to make something up yourself.

It consisted of a pair of glass sheets set at 90 degrees to each other and mounted so that the joining edge was uppermost (like an inverted V). The book is opened and placed face down on the edge so that the two facing pages are visible from underneath. This prevent stress and strain on the spine of the book. The weight of the book tends to naturally flatten the pages onto the glass too.

You'd probably want to use museum glass to minimise reflections and rig up some lighting or flash underneath to light the pages. Ideally you'd have two cameras, one for each page and take the two shots at once. Moving one camera from side to side is slower but doable.

Sorry that I don't have a drawing or picture. I hope that you can imagine it from my description.