I need to know how to do my own research when evaluating various overhead scanners against each other at various prices and evaluating various cameras against each other at various prices. I also need to understand how to evaluate an overhead scanner versus a camera (i.e. on a tripod, facing downward).
For illustration purposes only, I will give an example to clarify what I am referring to by overhead scanner: see this link.
By the term evaluate, I mean that I need to know what technical specifications to look for, in the cameras, and in the overhead scanners, and how they will affect the quality of the output. This information will help me to avoid (for example) having to make an Amazon purchase, see that the quality is insufficient, and then return the item.
If needed, I plan on telephoning the technical support of the manufacturer of the overhead scanner or camera, to ask about the technical specifications.
The remainder of this posting describes the purpose of my upcoming purchase (of either an overhead scanner or a [camera + tripod]), and the research that I have done so far.
As described in the scanner research section below, all I know about overhead scanners, is the vague idea that the more megapixels the better.
For cameras, I have the vague idea that it is partly about specifying the parameters correctly, and (perhaps) partly about using more expensive lenses.
As (also) discussed below, since I will necessarily be scaling the images to fit them into pdf pages, considerations may become tricky/problematic.
When I self-study a Math textbook, I keep my problem solutions in a pdf file that I do not print out. I also keep a separate pdf file that summarizes the chapter. This summary file includes my clarifications, my list of theorems or worked examples, the occasional diagram from the book, and the back-of-the-chapter pages of exercises, for reference.
All of the pages that I photograph or scan will go in the chapter summary pdf file, which I will print to paper.
Unfortunately, since the images will have to be framed in the page, I will probably have to scale the images, which will necessarily degrade the quality of the image.
My old camera has a mechanical on-off switch that often malfunctions. However, I will almost never be needing photographs or scans for anything other than the above Math documentation. If I can accomplish my Math goals via an overhead scanner, then I can keep the old camera for the once-every-5-years photograph that I may need to take.
Also, I subscribe to the Games World of Puzzles magazine, and I like to work the puzzles without actually writing in the magazine itself. Instead, I like to scan the page, save the image to my PC, and then print out the page image when I feel like attacking that particular puzzle.
For magazines and Math books combined, I expect to photograph or scan about 5-10 pages per week.
My research on Cameras
I recently posted a question concerning compensating for low light conditions. See this link.
Following up on suggestions from that posting, I experimented with my old Kodak EasyShare P712. I repositioned the four 60 watt lamps, set the iso to 100, the aperture to F8.0, and the shutter to 1/100 second. There was noticeable improvement. However, even though only I will be seeing the notebook, the images still are too fuzzy/grainy.
The P712 specifically instructs me to press the shutter half-way down, wait for the green light to indicate good focus and exposure, and then press the shutter all the way down. I did this, from about 18 inches away.
As juhist mentioned in the previous posting, I suspect that the problem is the camera itself. Beyond that, the (old) camera's malfunctioning on-off switch compels me to make a new purchase, anyway.
I also found this article on How could I get scanner-like images with a camera. The article is fairly old, so I suspect that the overhead scanner versus camera comparison is no longer valid. The article suggests that when using a camera, it is simply a matter of experimenting with the right parameters.
My research on Overhead Scanners
I purchased, experimented with, and then returned an 8mp $99 overhead scanner. The pictures were simply too grainy. I did not attempt to position the lamps around the overhead scanner. However, if need be, I can certainly do that each time.
Then, I experimented with my 7 year old brothers MFC-L2700DW (flatbed) printer/scanner/copier. I cut out a magazine page, manually placed it on the scanning bed, closed the scanning lid, and then chose the copy option on the printer. The printer created a reasonably clear crisp copy.
Then, keeping the magazine page in place, I ran 6 scans against the page. I varied the dpi to 300, 600, and 1200, and the output format to both jpeg and png. I then used an old software (paintshop pro) to fit the image to the page, and then print out the page.
All (6) images were somewhat grainier than the original copy. This is probably entirely due to the scaling. Unfortunately, I will always have to be scaling my images.
Attempting to use my flatbed printer/copier/scanner is probably not a good idea. I imagine that the constant wear and tear on the springs and hinges connected to the cover of the flatbed will make them erode. Beyond that, using a flatbed against a book is problematic.
In examining various overhead scanners, I noticed that the key difference between a $100 and $300 scanner is that 8mp goes to 20mp. I question whether this will help, since I will (still) have to scale the image to frame the image in the pdf page. The situation seems curious and suggests that overhead scanners are not generally used for book copying. Obviously, I am speculating here.
At 300 dpi, the magazine page has a canvas size of 2480 x 3437. If my understanding is correct, this roughly equates to 8.5 mp (megapixels).
I wonder if there are any other properties of an overhead scanner that I should be looking for, in addition to the stated number of megapixels.
Each of the Youtube videos on the topic have employed a camera, rather than an overhead scanner. This is leaving me with the impression that it will be hard to escape the truism that you get what you pay for. I do wonder, however, what the effect will be, with a modern camera, when the images are (still) subjected to the necessary scaling.
Note that attempting to present each of the images in landscape mode will be awkward, because my chapter summary pdf file will be presenting all of the (pdflatex) Math in portrait mode.
For what it's worth, I am somewhat mis-using the equipment-recommendation tag. That is, I am not asking about hardware versus budget considerations. I can evaluate that myself. I am asking which hardware specifications that I should be looking for, for my specific goal.