moire issue in shooting illustrations

[Jeff Sharpe]

In the last month or so, we have had a dramatic surge of images shot that end up with moire http://en.wikipedia.org/wiki/Moir%C3%A9_pattern I am leaning toward the cause as being a program issue, in part due to the explanation in this article on Descreen: http://www.scantips.com/basics6b.html "The array of dots used in the magazine halftone printing process is called a screen, and the software filter to remove moiré is called a Descreen filter. Scanner TWAIN driver software like Microtek ScanWizard and Umax VistaScan have very good Descreen filters that will greatly minimize moiré patterns. The Descreen filters have selectable parameters to match the screen frequency of the original image halftone (like newspaper or magazine). The additional Descreen processing does lengthen the scan time. It also greatly increases memory requirements for the processing the images. It is about the best solution, try it first. Moiré will always be a serious factor when scanning images in printed matter. "
We have shot over 8000 yearbooks in the last 2 years and only recently, around December 2011, has this become an issue. Now we are getting complaints from partners and are seeing this in every yearbook we shoot. We have had the Mark IIs for nearly a year. Did an upgrade change anything toward the end of last year or recently?
Some points:
- Does not seem to be a problem on the foldout
-Is not a problem when the text is out of focus

As we have plenty more yearbooks waiting to be scanned, this should be a priority.

Here are some of our examples:
http://www.archive.org/stream/grizzly19881989unse#page/76/mode/2up

http://www.archive.org/stream/royalpurple1927unse#page/n19/mode/2up

http://www.archive.org/stream/royalpurple1927unse#page/n29/mode/2up

Thanks,
Jeff

[Jeff Sharpe (jeffs)]

Oh it appears to be with the Mark II's only.
Here is an example of a Mark II: http://www.archive.org/stream/yucca1964nort#page/14/mode/2up
No moire, 5Ds http://www.archive.org/stream/thorntonite1944thor#page/n13/mode/2up