Blurring on One Side

[dansheffler]

Description:
So I have been using two A480s on my book scanner for over a year, they have shot several thousand pages apiece. Recently I noticed that the right side on both cameras is getting a little more blurred than it has in the past. This means that the top of the page for even pages, and the bottom of the page for odd pages are getting a little less crisp. I checked over just about everything that I think could be the cause. My lights are positioned well with even coverage over the whole page, in CHDK the cameras have a fixed subject distance value, they are very close to square with the page etc. etc.


Samples:
Here is a sample of an even page:

Notice that at high magnification the word "Introduction" at the top is decidedly less in focus than the words in the middle of the page. Notice particularly the serifs on the letters "N" and "D."

Here is a sample of a processed odd page:

Pages from Fine - Plato - 2000.pdf

(6.62 MiB) Downloaded 456 times

Notice that in the footnote text at the bottom there is a lot of breaking in rounded letters like "o," "c" and the top of "e." Also notice that the accents in "τὸ μὴ ὄν" are almost unreadable. Also notice that this variability in the font makes the file-size considerably bigger. Using Clearscan, a 300 page book is typically about 2-5 mb, but since this problem has started they are going up to about 15 mb.


Questions:
Has anyone else had problems like this?
Could this be a function of the cameras wearing out over time?
Does anyone have any suggestions for how to mitigate the problems?

[bnz]

Hm, f 3.2, 1/250s, iso 160. Have you tried a higher f-number for a wider depth-of-field to see what happens then? There is plenty of room here to a higher f-number.

[bnz]

Or alternatively, try to raise the ISO for an even faster shutter speed. I found that most of the new standard inspired builds (at least mine) where the cameras are mounted to the scanner itself, are very prone to minimal vibration as the page turning process causes movement that always somehow influences the camera mounts (actually, I started to use separate standard tripods pretty soon as they are decoupled from the book scanner).

[dansheffler]

FYI, after many hours of fiddling with this problem I am 90% sure that the issue is not with the cameras. The problem first appeared when I changed my lightbulbs from a frosted kind to a clear kind. When I did this there appeared very slight hotspots in the light and I believe that the presence of just slightly brighter light on the areas of the page in question caused them to get just ever so washed out which looked like a blur. By readjusting the lights so that the center of the light is some distance off the pages I have achieved a much more even light.