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01-22-2011, 11:01 AM   #1
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lens for document photos

I'm planning a trip to do some work in an archive, and I'd like to try to photograph documents I want. Once the jpeg files are turned into pdfs I can search them -- and in the meantime, I won't have the problem of lugging around and storing the paper.
Anyway, what lens? A wide macro? I know it's not either of the kit lenses that came with my k-x (DA L 18-55 and 50-200).

01-22-2011, 11:18 AM   #2
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Morning,

Your questions spawns a lot more questions, and probably a bit of experimentation on your part before you go "live".
  1. What is the available light going to be in the location?
  2. What are the physical dimensions of documents you are interested in? Are they bound in a book? Will the book lay flat? How far will the camera be from the documents?
  3. Other than the camera, what additional equipment can you bring - a document stand to hold the camera perpendicular to the plane of the document, etc.?
  4. Is accurate color replication necessary?
If the lighting is poor, you will need to use a fast lens (f2.8 to f1.8), which will limit your depth of field (DoF). Your DoF will matter a lot if it is books your are going to photograph since they will probably not lie flat. Thus, part of the page will be in focus while other areas are out of focus.

Also, are you sure you can convert JPG into PDFs so that you can convert to characters accurately?

Here are some links that may help.
Just some thoughts...

01-22-2011, 11:47 AM   #3
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As far as I know right now, I'll be working with sheets of paper, not books -- with a few photos of photos. A full copy stand would be too big to travel with, so I was looking at this sort of setup:
Tabletop monopod, macro photography, mini tripod, camera stand, copy stand
At my first stop the lighting is pretty good (bright overhead with desk lighting as well). But since this is something that I'd likely do elsewhere later, a fast lens wouldn't hurt.
I've scanned documents to jpeg and then converted to pdf, so I'm assuming, maybe wrongly, that what I have in mind will work.
01-22-2011, 12:02 PM   #4
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My first thought is, if you're shooting unbound sheets and have some flat working space, why not just take a small scanner and laptop/netbook? That's much less complicated than any sort of photographic setup. Shooting documents without a copy stand is quite bothersome. If forced to (as I was a few years ago) I'd use an advanced P&S, not a dSLR.

01-22-2011, 12:55 PM   #5
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Good light is the most important in photographing hardcopy documents, but the lens is not as important - I have effectively archived documents in JPG format using a fast fifty at about f/5.6, but have done the same with the kit lens at f/8 and came out with very acceptable results.
01-22-2011, 01:37 PM   #6
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Do you have an iPhone?

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01-22-2011, 02:20 PM   #7
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Hi louieh,

The traditional solution is a shorter dedicated macro to get very flat field and low levels of distortion. A good 50 mm Macro is the traditional choice, and would work well with an APS-C digital. Your zooms will probably not be as suitable because of distortion, but it really depends on how fussy you're going to be about the appearance of the images. The flat field aspect is important because you want as much consistency from the center to the edges and corners as possible for readability. Manual focus lenses should be considered as they will have virtually the same optical quality, cost a lot less, and AF will not be an advantage in this type of shooting. If you provide your own light source, speed should not be a factor, and it's been said that there aren't any bad dedicated macros, so brand shouldn't make too much of a difference, but the Pentax Macros have always been top shelf, so any of these would be a good choice.

You should use a versatile positioning tripod or copy stand to ensure that the camera is consistently very square with the document. This is important to both your final results and to the workflow when you're shooting.

Also, lighting is very important, and should be at about 45 to the document to prevent hot spots and reflections, so you might plan on providing consistent source(s) of light if you're going to be shooting in different locations.

Scott
01-22-2011, 02:47 PM   #8
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QuoteOriginally posted by louieh Quote
I'm planning a trip to do some work in an archive, and I'd like to try to photograph documents I want. Once the jpeg files are turned into pdfs I can search them -- and in the meantime, I won't have the problem of lugging around and storing the paper.
Anyway, what lens? A wide macro? I know it's not either of the kit lenses that came with my k-x (DA L 18-55 and 50-200).
I'm presuming the scanner option is a bust for whatever reason, and that if you are going to do this it has to be done with a camera.
Holding the camera horizontal is always the problem with this.
The little monopod looks cool. I suspect it would work well enough with the Kx. One of the advantages of a light camera is lightweight support equipment often works.
I think either the 35 macro or 50 macro would be ideal, but even a 50 f/2 and a short extension tube will probably work well enough.


Changing the files to pdf is, as you know, not a problem.
I believe it is one of the save as options in Photoshop.

01-22-2011, 02:51 PM   #9
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You already received some good advice.

I have done some photographs of old documents in library, typically some pre-1950 documents and books, incl. some handwritten manuscripts. A few comments come in mind:

1- use a prime lens to minimise any distortion

2- good lighting is essential (do not use the camera flash, better use bouncing flash light for indirect lighting)

3- you do not need some high resolution jpegs; some 2 Mp one-star quality shots will be plenty enough, especially if you do OCR of the PDF.

4- a focal length of 25-40 mm is probably within the good range to photograph A4 pages (I used my FA31mm quite successfully)

5- on MF vs AF, I used both and the results are close.


Hope that the comments will help...
01-22-2011, 03:39 PM   #10
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Wow, thanks, a lot of good advice. Some archives I know I will be using again (Library of Congress and National Archives,for example) allow cameras but not scanners. Some won't allow cameras for that matter, but that's less true with my usual stops.
I don't have an iPhone (though I read that Verizon, the carrier I'm stuck with, has gotten on board. But it looks like my choices are:
1. fast prime, macro or not, 50mm tops, AF not an issue, with a tripod/table monopod arrangement and a remote
2. a capable point and shoot, probably with a cheaper monopod
3. an iPhone
At this point I have none of these things. (My last decent point and shoot flipped with me in a kayak, and the waterproof bag turned out to be a little less than that). Since I'm not ready for a new phone yet, and I'd have other uses for the lens, it looks like an excuse to shop.
Thanks for the pointers on what to look for.
01-22-2011, 05:10 PM   #11
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There are several stand designs that might work for you (portable), including something like this...The minimum focusing distance on an A 50mm is 45cm or 18 inches. For the macro it is something like 23cm or 10 inches.

Something that you might want to consider is a remote shutter release. For your Kx you would need an IR unit. This way it might make your work flow a bit easier.

At work we had some old documents converted into PDFs and the old typewriter font used did not translate well via the OCR conversion (probably a ribbon and unequal pressure on the keys). It was hit and miss...

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